1198 lines
32 KiB
C
1198 lines
32 KiB
C
/*-
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* SPDX-License-Identifier: BSD-3-Clause
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*
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* Copyright (c) 1998 Matthew Dillon. All Rights Reserved.
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
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* OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
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* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
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* GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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/*
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* BLIST.C - Bitmap allocator/deallocator, using a radix tree with hinting
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*
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* This module implements a general bitmap allocator/deallocator. The
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* allocator eats around 2 bits per 'block'. The module does not
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* try to interpret the meaning of a 'block' other than to return
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* SWAPBLK_NONE on an allocation failure.
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*
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* A radix tree controls access to pieces of the bitmap, and includes
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* auxiliary information at each interior node about the availabilty of
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* contiguous free blocks in the subtree rooted at that node. Two radix
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* constants are involved: one for the size of the bitmaps contained in the
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* leaf nodes (BLIST_BMAP_RADIX), and one for the number of descendents of
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* each of the meta (interior) nodes (BLIST_META_RADIX). Each subtree is
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* associated with a range of blocks. The root of any subtree stores a
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* hint field that defines an upper bound on the size of the largest
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* allocation that can begin in the associated block range. A hint is an
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* upper bound on a potential allocation, but not necessarily a tight upper
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* bound.
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*
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* The bitmap field in each node directs the search for available blocks.
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* For a leaf node, a bit is set if the corresponding block is free. For a
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* meta node, a bit is set if the corresponding subtree contains a free
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* block somewhere within it. The search at a meta node considers only
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* children of that node that represent a range that includes a free block.
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*
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* The hinting greatly increases code efficiency for allocations while
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* the general radix structure optimizes both allocations and frees. The
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* radix tree should be able to operate well no matter how much
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* fragmentation there is and no matter how large a bitmap is used.
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*
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* The blist code wires all necessary memory at creation time. Neither
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* allocations nor frees require interaction with the memory subsystem.
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* The non-blocking nature of allocations and frees is required by swap
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* code (vm/swap_pager.c).
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*
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* LAYOUT: The radix tree is laid out recursively using a linear array.
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* Each meta node is immediately followed (laid out sequentially in
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* memory) by BLIST_META_RADIX lower level nodes. This is a recursive
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* structure but one that can be easily scanned through a very simple
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* 'skip' calculation. The memory allocation is only large enough to
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* cover the number of blocks requested at creation time. Nodes that
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* represent blocks beyond that limit, nodes that would never be read
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* or written, are not allocated, so that the last of the
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* BLIST_META_RADIX lower level nodes of a some nodes may not be
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* allocated.
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*
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* NOTE: the allocator cannot currently allocate more than
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* BLIST_BMAP_RADIX blocks per call. It will panic with 'allocation too
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* large' if you try. This is an area that could use improvement. The
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* radix is large enough that this restriction does not effect the swap
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* system, though. Currently only the allocation code is affected by
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* this algorithmic unfeature. The freeing code can handle arbitrary
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* ranges.
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*
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* This code can be compiled stand-alone for debugging.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#ifdef _KERNEL
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/lock.h>
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#include <sys/kernel.h>
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#include <sys/blist.h>
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#include <sys/malloc.h>
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#include <sys/sbuf.h>
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#include <sys/proc.h>
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#include <sys/mutex.h>
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#else
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#ifndef BLIST_NO_DEBUG
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#define BLIST_DEBUG
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#endif
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#include <sys/errno.h>
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#include <sys/types.h>
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#include <sys/malloc.h>
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#include <sys/sbuf.h>
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#include <assert.h>
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#include <stdio.h>
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#include <string.h>
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#include <stddef.h>
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#include <stdlib.h>
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#include <stdarg.h>
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#include <stdbool.h>
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#define bitcount64(x) __bitcount64((uint64_t)(x))
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#define malloc(a,b,c) calloc(a, 1)
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#define free(a,b) free(a)
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#define ummin(a,b) ((a) < (b) ? (a) : (b))
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#define imin(a,b) ((a) < (b) ? (a) : (b))
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#define KASSERT(a,b) assert(a)
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#include <sys/blist.h>
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#endif
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/*
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* static support functions
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*/
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static daddr_t blst_leaf_alloc(blmeta_t *scan, daddr_t blk,
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int *count, int maxcount);
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static daddr_t blst_meta_alloc(blmeta_t *scan, daddr_t cursor, int *count,
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int maxcount, u_daddr_t radix);
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static void blst_leaf_free(blmeta_t *scan, daddr_t relblk, int count);
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static void blst_meta_free(blmeta_t *scan, daddr_t freeBlk, daddr_t count,
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u_daddr_t radix);
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static void blst_copy(blmeta_t *scan, daddr_t blk, daddr_t radix,
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blist_t dest, daddr_t count);
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static daddr_t blst_leaf_fill(blmeta_t *scan, daddr_t blk, int count);
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static daddr_t blst_meta_fill(blmeta_t *scan, daddr_t allocBlk, daddr_t count,
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u_daddr_t radix);
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#ifndef _KERNEL
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static void blst_radix_print(blmeta_t *scan, daddr_t blk, daddr_t radix,
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int tab);
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#endif
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#ifdef _KERNEL
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static MALLOC_DEFINE(M_SWAP, "SWAP", "Swap space");
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#endif
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_Static_assert(BLIST_BMAP_RADIX % BLIST_META_RADIX == 0,
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"radix divisibility error");
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#define BLIST_BMAP_MASK (BLIST_BMAP_RADIX - 1)
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#define BLIST_META_MASK (BLIST_META_RADIX - 1)
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/*
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* For a subtree that can represent the state of up to 'radix' blocks, the
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* number of leaf nodes of the subtree is L=radix/BLIST_BMAP_RADIX. If 'm'
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* is short for BLIST_META_RADIX, then for a tree of height h with L=m**h
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* leaf nodes, the total number of tree nodes is 1 + m + m**2 + ... + m**h,
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* or, equivalently, (m**(h+1)-1)/(m-1). This quantity is called 'skip'
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* in the 'meta' functions that process subtrees. Since integer division
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* discards remainders, we can express this computation as
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* skip = (m * m**h) / (m - 1)
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* skip = (m * (radix / BLIST_BMAP_RADIX)) / (m - 1)
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* and since m divides BLIST_BMAP_RADIX, we can simplify further to
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* skip = (radix / (BLIST_BMAP_RADIX / m)) / (m - 1)
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* skip = radix / ((BLIST_BMAP_RADIX / m) * (m - 1))
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* so that simple integer division by a constant can safely be used for the
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* calculation.
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*/
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static inline daddr_t
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radix_to_skip(daddr_t radix)
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{
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return (radix /
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((BLIST_BMAP_RADIX / BLIST_META_RADIX) * BLIST_META_MASK));
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}
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/*
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* Provide a mask with count bits set, starting as position n.
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*/
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static inline u_daddr_t
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bitrange(int n, int count)
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{
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return (((u_daddr_t)-1 << n) &
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((u_daddr_t)-1 >> (BLIST_BMAP_RADIX - (n + count))));
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}
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/*
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* Find the first bit set in a u_daddr_t.
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*/
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static inline int
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generic_bitpos(u_daddr_t mask)
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{
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int hi, lo, mid;
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lo = 0;
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hi = BLIST_BMAP_RADIX;
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while (lo + 1 < hi) {
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mid = (lo + hi) >> 1;
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if (mask & bitrange(0, mid))
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hi = mid;
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else
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lo = mid;
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}
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return (lo);
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}
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static inline int
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bitpos(u_daddr_t mask)
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{
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switch (sizeof(mask)) {
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#ifdef HAVE_INLINE_FFSLL
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case sizeof(long long):
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return (ffsll(mask) - 1);
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#endif
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#ifdef HAVE_INLINE_FFS
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case sizeof(int):
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return (ffs(mask) - 1);
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#endif
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default:
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return (generic_bitpos(mask));
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}
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}
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/*
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* blist_create() - create a blist capable of handling up to the specified
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* number of blocks
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*
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* blocks - must be greater than 0
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* flags - malloc flags
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*
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* The smallest blist consists of a single leaf node capable of
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* managing BLIST_BMAP_RADIX blocks.
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*/
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blist_t
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blist_create(daddr_t blocks, int flags)
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{
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blist_t bl;
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u_daddr_t nodes, radix;
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KASSERT(blocks > 0, ("invalid block count"));
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/*
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* Calculate the radix and node count used for scanning.
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*/
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nodes = 1;
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radix = BLIST_BMAP_RADIX;
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while (radix <= blocks) {
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nodes += 1 + (blocks - 1) / radix;
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radix *= BLIST_META_RADIX;
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}
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bl = malloc(offsetof(struct blist, bl_root[nodes]), M_SWAP, flags |
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M_ZERO);
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if (bl == NULL)
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return (NULL);
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bl->bl_blocks = blocks;
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bl->bl_radix = radix;
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#if defined(BLIST_DEBUG)
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printf(
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"BLIST representing %lld blocks (%lld MB of swap)"
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", requiring %lldK of ram\n",
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(long long)bl->bl_blocks,
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(long long)bl->bl_blocks * 4 / 1024,
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(long long)(nodes * sizeof(blmeta_t) + 1023) / 1024
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);
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printf("BLIST raw radix tree contains %lld records\n",
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(long long)nodes);
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#endif
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return (bl);
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}
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void
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blist_destroy(blist_t bl)
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{
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free(bl, M_SWAP);
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}
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/*
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* blist_alloc() - reserve space in the block bitmap. Return the base
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* of a contiguous region or SWAPBLK_NONE if space could
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* not be allocated.
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*/
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daddr_t
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blist_alloc(blist_t bl, int *count, int maxcount)
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{
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daddr_t blk, cursor;
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KASSERT(*count <= maxcount,
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("invalid parameters %d > %d", *count, maxcount));
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KASSERT(*count <= BLIST_MAX_ALLOC,
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("minimum allocation too large: %d", *count));
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/*
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* This loop iterates at most twice. An allocation failure in the
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* first iteration leads to a second iteration only if the cursor was
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* non-zero. When the cursor is zero, an allocation failure will
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* stop further iterations.
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*/
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for (cursor = bl->bl_cursor;; cursor = 0) {
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blk = blst_meta_alloc(bl->bl_root, cursor, count, maxcount,
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bl->bl_radix);
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if (blk != SWAPBLK_NONE) {
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bl->bl_avail -= *count;
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bl->bl_cursor = blk + *count;
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if (bl->bl_cursor == bl->bl_blocks)
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bl->bl_cursor = 0;
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return (blk);
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}
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if (cursor == 0)
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return (SWAPBLK_NONE);
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}
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}
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/*
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* blist_avail() - return the number of free blocks.
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*/
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daddr_t
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blist_avail(blist_t bl)
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{
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return (bl->bl_avail);
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}
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/*
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* blist_free() - free up space in the block bitmap. Return the base
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* of a contiguous region.
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*/
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void
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blist_free(blist_t bl, daddr_t blkno, daddr_t count)
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{
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KASSERT(blkno >= 0 && blkno + count <= bl->bl_blocks,
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("freeing invalid range: blkno %jx, count %d, blocks %jd",
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(uintmax_t)blkno, (int)count, (uintmax_t)bl->bl_blocks));
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blst_meta_free(bl->bl_root, blkno, count, bl->bl_radix);
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bl->bl_avail += count;
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}
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/*
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* blist_fill() - mark a region in the block bitmap as off-limits
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* to the allocator (i.e. allocate it), ignoring any
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* existing allocations. Return the number of blocks
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* actually filled that were free before the call.
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*/
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daddr_t
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blist_fill(blist_t bl, daddr_t blkno, daddr_t count)
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{
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daddr_t filled;
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KASSERT(blkno >= 0 && blkno + count <= bl->bl_blocks,
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("filling invalid range: blkno %jx, count %d, blocks %jd",
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(uintmax_t)blkno, (int)count, (uintmax_t)bl->bl_blocks));
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filled = blst_meta_fill(bl->bl_root, blkno, count, bl->bl_radix);
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bl->bl_avail -= filled;
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return (filled);
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}
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/*
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* blist_resize() - resize an existing radix tree to handle the
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* specified number of blocks. This will reallocate
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* the tree and transfer the previous bitmap to the new
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* one. When extending the tree you can specify whether
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* the new blocks are to left allocated or freed.
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*/
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void
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blist_resize(blist_t *pbl, daddr_t count, int freenew, int flags)
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{
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blist_t newbl = blist_create(count, flags);
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blist_t save = *pbl;
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*pbl = newbl;
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if (count > save->bl_blocks)
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count = save->bl_blocks;
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blst_copy(save->bl_root, 0, save->bl_radix, newbl, count);
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/*
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* If resizing upwards, should we free the new space or not?
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*/
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if (freenew && count < newbl->bl_blocks) {
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blist_free(newbl, count, newbl->bl_blocks - count);
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}
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blist_destroy(save);
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}
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#ifdef BLIST_DEBUG
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/*
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* blist_print() - dump radix tree
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*/
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void
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blist_print(blist_t bl)
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{
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printf("BLIST avail = %jd, cursor = %08jx {\n",
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(uintmax_t)bl->bl_avail, (uintmax_t)bl->bl_cursor);
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if (bl->bl_root->bm_bitmap != 0)
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blst_radix_print(bl->bl_root, 0, bl->bl_radix, 4);
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printf("}\n");
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}
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#endif
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static const u_daddr_t fib[] = {
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1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377, 610, 987, 1597, 2584,
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4181, 6765, 10946, 17711, 28657, 46368, 75025, 121393, 196418, 317811,
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514229, 832040, 1346269, 2178309, 3524578,
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};
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|
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/*
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* Use 'gap' to describe a maximal range of unallocated blocks/bits.
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*/
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struct gap_stats {
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daddr_t start; /* current gap start, or SWAPBLK_NONE */
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daddr_t num; /* number of gaps observed */
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daddr_t max; /* largest gap size */
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daddr_t avg; /* average gap size */
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daddr_t err; /* sum - num * avg */
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daddr_t histo[nitems(fib)]; /* # gaps in each size range */
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int max_bucket; /* last histo elt with nonzero val */
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};
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|
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/*
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* gap_stats_counting() - is the state 'counting 1 bits'?
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* or 'skipping 0 bits'?
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*/
|
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static inline bool
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gap_stats_counting(const struct gap_stats *stats)
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|
{
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|
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return (stats->start != SWAPBLK_NONE);
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}
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|
|
|
/*
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|
* init_gap_stats() - initialize stats on gap sizes
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|
*/
|
|
static inline void
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init_gap_stats(struct gap_stats *stats)
|
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{
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bzero(stats, sizeof(*stats));
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stats->start = SWAPBLK_NONE;
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}
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|
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/*
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* update_gap_stats() - update stats on gap sizes
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*/
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static void
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update_gap_stats(struct gap_stats *stats, daddr_t posn)
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{
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daddr_t size;
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int hi, lo, mid;
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|
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if (!gap_stats_counting(stats)) {
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stats->start = posn;
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return;
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}
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size = posn - stats->start;
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stats->start = SWAPBLK_NONE;
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if (size > stats->max)
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stats->max = size;
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|
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/*
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* Find the fibonacci range that contains size,
|
|
* expecting to find it in an early range.
|
|
*/
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lo = 0;
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hi = 1;
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while (hi < nitems(fib) && fib[hi] <= size) {
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lo = hi;
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hi *= 2;
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}
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if (hi >= nitems(fib))
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hi = nitems(fib);
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while (lo + 1 != hi) {
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mid = (lo + hi) >> 1;
|
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if (fib[mid] <= size)
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lo = mid;
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else
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hi = mid;
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}
|
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stats->histo[lo]++;
|
|
if (lo > stats->max_bucket)
|
|
stats->max_bucket = lo;
|
|
stats->err += size - stats->avg;
|
|
stats->num++;
|
|
stats->avg += stats->err / stats->num;
|
|
stats->err %= stats->num;
|
|
}
|
|
|
|
/*
|
|
* dump_gap_stats() - print stats on gap sizes
|
|
*/
|
|
static inline void
|
|
dump_gap_stats(const struct gap_stats *stats, struct sbuf *s)
|
|
{
|
|
int i;
|
|
|
|
sbuf_printf(s, "number of maximal free ranges: %jd\n",
|
|
(intmax_t)stats->num);
|
|
sbuf_printf(s, "largest free range: %jd\n", (intmax_t)stats->max);
|
|
sbuf_printf(s, "average maximal free range size: %jd\n",
|
|
(intmax_t)stats->avg);
|
|
sbuf_printf(s, "number of maximal free ranges of different sizes:\n");
|
|
sbuf_printf(s, " count | size range\n");
|
|
sbuf_printf(s, " ----- | ----------\n");
|
|
for (i = 0; i < stats->max_bucket; i++) {
|
|
if (stats->histo[i] != 0) {
|
|
sbuf_printf(s, "%20jd | ",
|
|
(intmax_t)stats->histo[i]);
|
|
if (fib[i] != fib[i + 1] - 1)
|
|
sbuf_printf(s, "%jd to %jd\n", (intmax_t)fib[i],
|
|
(intmax_t)fib[i + 1] - 1);
|
|
else
|
|
sbuf_printf(s, "%jd\n", (intmax_t)fib[i]);
|
|
}
|
|
}
|
|
sbuf_printf(s, "%20jd | ", (intmax_t)stats->histo[i]);
|
|
if (stats->histo[i] > 1)
|
|
sbuf_printf(s, "%jd to %jd\n", (intmax_t)fib[i],
|
|
(intmax_t)stats->max);
|
|
else
|
|
sbuf_printf(s, "%jd\n", (intmax_t)stats->max);
|
|
}
|
|
|
|
/*
|
|
* blist_stats() - dump radix tree stats
|
|
*/
|
|
void
|
|
blist_stats(blist_t bl, struct sbuf *s)
|
|
{
|
|
struct gap_stats gstats;
|
|
struct gap_stats *stats = &gstats;
|
|
daddr_t i, nodes, radix;
|
|
u_daddr_t diff, mask;
|
|
int digit;
|
|
|
|
init_gap_stats(stats);
|
|
nodes = 0;
|
|
i = bl->bl_radix;
|
|
while (i < bl->bl_radix + bl->bl_blocks) {
|
|
/*
|
|
* Find max size subtree starting at i.
|
|
*/
|
|
radix = BLIST_BMAP_RADIX;
|
|
while (((i / radix) & BLIST_META_MASK) == 0)
|
|
radix *= BLIST_META_RADIX;
|
|
|
|
/*
|
|
* Check for skippable subtrees starting at i.
|
|
*/
|
|
while (radix > BLIST_BMAP_RADIX) {
|
|
if (bl->bl_root[nodes].bm_bitmap == 0) {
|
|
if (gap_stats_counting(stats))
|
|
update_gap_stats(stats, i);
|
|
break;
|
|
}
|
|
|
|
/*
|
|
* Skip subtree root.
|
|
*/
|
|
nodes++;
|
|
radix /= BLIST_META_RADIX;
|
|
}
|
|
if (radix == BLIST_BMAP_RADIX) {
|
|
/*
|
|
* Scan leaf.
|
|
*/
|
|
mask = bl->bl_root[nodes].bm_bitmap;
|
|
diff = mask ^ (mask << 1);
|
|
if (gap_stats_counting(stats))
|
|
diff ^= 1;
|
|
while (diff != 0) {
|
|
digit = bitpos(diff);
|
|
update_gap_stats(stats, i + digit);
|
|
diff ^= bitrange(digit, 1);
|
|
}
|
|
}
|
|
nodes += radix_to_skip(radix);
|
|
i += radix;
|
|
}
|
|
update_gap_stats(stats, i);
|
|
dump_gap_stats(stats, s);
|
|
}
|
|
|
|
/************************************************************************
|
|
* ALLOCATION SUPPORT FUNCTIONS *
|
|
************************************************************************
|
|
*
|
|
* These support functions do all the actual work. They may seem
|
|
* rather longish, but that's because I've commented them up. The
|
|
* actual code is straight forward.
|
|
*
|
|
*/
|
|
|
|
/*
|
|
* BLST_NEXT_LEAF_ALLOC() - allocate the blocks starting with the next leaf.
|
|
*
|
|
* 'scan' is a leaf node, and its first block is at address 'start'. The
|
|
* next leaf node could be adjacent, or several nodes away if the least
|
|
* common ancestor of 'scan' and its neighbor is several levels up. Use
|
|
* addresses to determine how many meta-nodes lie between the leaves. If
|
|
* sequence of leaves starting with the next one has enough initial bits
|
|
* set, clear them and clear the bits in the meta nodes on the path up to
|
|
* the least common ancestor to mark any subtrees made completely empty.
|
|
*/
|
|
static int
|
|
blst_next_leaf_alloc(blmeta_t *scan, daddr_t start, int count, int maxcount)
|
|
{
|
|
u_daddr_t radix;
|
|
daddr_t blk;
|
|
int avail, digit;
|
|
|
|
start += BLIST_BMAP_RADIX;
|
|
for (blk = start; blk - start < maxcount; blk += BLIST_BMAP_RADIX) {
|
|
/* Skip meta-nodes, as long as they promise more free blocks. */
|
|
radix = BLIST_BMAP_RADIX;
|
|
while (((++scan)->bm_bitmap & 1) == 1 &&
|
|
((blk / radix) & BLIST_META_MASK) == 0)
|
|
radix *= BLIST_META_RADIX;
|
|
if (~scan->bm_bitmap != 0) {
|
|
/*
|
|
* Either there is no next leaf with any free blocks,
|
|
* or we've reached the next leaf and found that some
|
|
* of its blocks are not free. In the first case,
|
|
* bitpos() returns zero here.
|
|
*/
|
|
avail = blk - start + bitpos(~scan->bm_bitmap);
|
|
if (avail < count || avail == 0) {
|
|
/*
|
|
* There isn't a next leaf with enough free
|
|
* blocks at its beginning to bother
|
|
* allocating.
|
|
*/
|
|
return (avail);
|
|
}
|
|
maxcount = imin(avail, maxcount);
|
|
if (maxcount % BLIST_BMAP_RADIX == 0) {
|
|
/*
|
|
* There was no next leaf. Back scan up to
|
|
* last leaf.
|
|
*/
|
|
--scan;
|
|
while (radix != BLIST_BMAP_RADIX) {
|
|
radix /= BLIST_META_RADIX;
|
|
--scan;
|
|
}
|
|
blk -= BLIST_BMAP_RADIX;
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* 'scan' is the last leaf that provides blocks. Clear from 1 to
|
|
* BLIST_BMAP_RADIX bits to represent the allocation of those last
|
|
* blocks.
|
|
*/
|
|
if (maxcount % BLIST_BMAP_RADIX != 0)
|
|
scan->bm_bitmap &= ~bitrange(0, maxcount % BLIST_BMAP_RADIX);
|
|
else
|
|
scan->bm_bitmap = 0;
|
|
|
|
for (;;) {
|
|
/* Back up over meta-nodes, clearing bits if necessary. */
|
|
blk -= BLIST_BMAP_RADIX;
|
|
radix = BLIST_BMAP_RADIX;
|
|
while ((digit = ((blk / radix) & BLIST_META_MASK)) == 0) {
|
|
if ((scan--)->bm_bitmap == 0)
|
|
scan->bm_bitmap ^= 1;
|
|
radix *= BLIST_META_RADIX;
|
|
}
|
|
if ((scan--)->bm_bitmap == 0)
|
|
scan[-digit * radix_to_skip(radix)].bm_bitmap ^=
|
|
(u_daddr_t)1 << digit;
|
|
|
|
if (blk == start)
|
|
break;
|
|
/* Clear all the bits of this leaf. */
|
|
scan->bm_bitmap = 0;
|
|
}
|
|
return (maxcount);
|
|
}
|
|
|
|
/*
|
|
* BLST_LEAF_ALLOC() - allocate at a leaf in the radix tree (a bitmap).
|
|
*
|
|
* This function is the core of the allocator. Its execution time is
|
|
* proportional to log(count), plus height of the tree if the allocation
|
|
* crosses a leaf boundary.
|
|
*/
|
|
static daddr_t
|
|
blst_leaf_alloc(blmeta_t *scan, daddr_t blk, int *count, int maxcount)
|
|
{
|
|
u_daddr_t mask;
|
|
int bighint, count1, hi, lo, num_shifts;
|
|
|
|
count1 = *count - 1;
|
|
num_shifts = fls(count1);
|
|
mask = ~scan->bm_bitmap;
|
|
while ((mask & (mask + 1)) != 0 && num_shifts > 0) {
|
|
/*
|
|
* If bit i is 0 in mask, then bits in [i, i + (count1 >>
|
|
* num_shifts)] are 1 in scan->bm_bitmap. Reduce num_shifts to
|
|
* 0, while preserving this invariant. The updates to mask
|
|
* leave fewer bits 0, but each bit that remains 0 represents a
|
|
* longer string of consecutive 1-bits in scan->bm_bitmap. If
|
|
* more updates to mask cannot set more bits, because mask is
|
|
* partitioned with all 1 bits following all 0 bits, the loop
|
|
* terminates immediately.
|
|
*/
|
|
num_shifts--;
|
|
mask |= mask >> ((count1 >> num_shifts) + 1) / 2;
|
|
}
|
|
bighint = count1 >> num_shifts;
|
|
if (~mask == 0) {
|
|
/*
|
|
* Update bighint. There is no allocation bigger than
|
|
* count1 >> num_shifts starting in this leaf.
|
|
*/
|
|
scan->bm_bighint = bighint;
|
|
return (SWAPBLK_NONE);
|
|
}
|
|
|
|
/* Discard any candidates that appear before blk. */
|
|
if ((blk & BLIST_BMAP_MASK) != 0) {
|
|
if ((~mask & bitrange(0, blk & BLIST_BMAP_MASK)) != 0) {
|
|
/* Grow bighint in case all discarded bits are set. */
|
|
bighint += blk & BLIST_BMAP_MASK;
|
|
mask |= bitrange(0, blk & BLIST_BMAP_MASK);
|
|
if (~mask == 0) {
|
|
scan->bm_bighint = bighint;
|
|
return (SWAPBLK_NONE);
|
|
}
|
|
}
|
|
blk -= blk & BLIST_BMAP_MASK;
|
|
}
|
|
|
|
/*
|
|
* The least significant set bit in mask marks the start of the first
|
|
* available range of sufficient size. Find its position.
|
|
*/
|
|
lo = bitpos(~mask);
|
|
|
|
/*
|
|
* Find how much space is available starting at that position.
|
|
*/
|
|
if ((mask & (mask + 1)) != 0) {
|
|
/* Count the 1 bits starting at position lo. */
|
|
hi = bitpos(mask & (mask + 1)) + count1;
|
|
if (maxcount < hi - lo)
|
|
hi = lo + maxcount;
|
|
*count = hi - lo;
|
|
mask = ~bitrange(lo, *count);
|
|
} else if (maxcount <= BLIST_BMAP_RADIX - lo) {
|
|
/* All the blocks we can use are available here. */
|
|
hi = lo + maxcount;
|
|
*count = maxcount;
|
|
mask = ~bitrange(lo, *count);
|
|
if (hi == BLIST_BMAP_RADIX)
|
|
scan->bm_bighint = bighint;
|
|
} else {
|
|
/* Check next leaf for some of the blocks we want or need. */
|
|
count1 = *count - (BLIST_BMAP_RADIX - lo);
|
|
maxcount -= BLIST_BMAP_RADIX - lo;
|
|
hi = blst_next_leaf_alloc(scan, blk, count1, maxcount);
|
|
if (hi < count1)
|
|
/*
|
|
* The next leaf cannot supply enough blocks to reach
|
|
* the minimum required allocation. The hint cannot be
|
|
* updated, because the same allocation request could
|
|
* be satisfied later, by this leaf, if the state of
|
|
* the next leaf changes, and without any changes to
|
|
* this leaf.
|
|
*/
|
|
return (SWAPBLK_NONE);
|
|
*count = BLIST_BMAP_RADIX - lo + hi;
|
|
scan->bm_bighint = bighint;
|
|
}
|
|
|
|
/* Clear the allocated bits from this leaf. */
|
|
scan->bm_bitmap &= mask;
|
|
return (blk + lo);
|
|
}
|
|
|
|
/*
|
|
* blist_meta_alloc() - allocate at a meta in the radix tree.
|
|
*
|
|
* Attempt to allocate at a meta node. If we can't, we update
|
|
* bighint and return a failure. Updating bighint optimize future
|
|
* calls that hit this node. We have to check for our collapse cases
|
|
* and we have a few optimizations strewn in as well.
|
|
*/
|
|
static daddr_t
|
|
blst_meta_alloc(blmeta_t *scan, daddr_t cursor, int *count,
|
|
int maxcount, u_daddr_t radix)
|
|
{
|
|
daddr_t blk, i, r, skip;
|
|
u_daddr_t mask;
|
|
bool scan_from_start;
|
|
int digit;
|
|
|
|
if (radix == BLIST_BMAP_RADIX)
|
|
return (blst_leaf_alloc(scan, cursor, count, maxcount));
|
|
blk = cursor & -radix;
|
|
scan_from_start = (cursor == blk);
|
|
radix /= BLIST_META_RADIX;
|
|
skip = radix_to_skip(radix);
|
|
mask = scan->bm_bitmap;
|
|
|
|
/* Discard any candidates that appear before cursor. */
|
|
digit = (cursor / radix) & BLIST_META_MASK;
|
|
mask &= (u_daddr_t)-1 << digit;
|
|
if (mask == 0)
|
|
return (SWAPBLK_NONE);
|
|
|
|
/*
|
|
* If the first try is for a block that includes the cursor, pre-undo
|
|
* the digit * radix offset in the first call; otherwise, ignore the
|
|
* cursor entirely.
|
|
*/
|
|
if (((mask >> digit) & 1) == 1)
|
|
cursor -= digit * radix;
|
|
else
|
|
cursor = blk;
|
|
|
|
/*
|
|
* Examine the nonempty subtree associated with each bit set in mask.
|
|
*/
|
|
do {
|
|
digit = bitpos(mask);
|
|
i = 1 + digit * skip;
|
|
if (*count <= scan[i].bm_bighint) {
|
|
/*
|
|
* The allocation might fit beginning in the i'th subtree.
|
|
*/
|
|
r = blst_meta_alloc(&scan[i], cursor + digit * radix,
|
|
count, maxcount, radix);
|
|
if (r != SWAPBLK_NONE) {
|
|
if (scan[i].bm_bitmap == 0)
|
|
scan->bm_bitmap ^= bitrange(digit, 1);
|
|
return (r);
|
|
}
|
|
}
|
|
cursor = blk;
|
|
} while ((mask ^= bitrange(digit, 1)) != 0);
|
|
|
|
/*
|
|
* We couldn't allocate count in this subtree. If the whole tree was
|
|
* scanned, and the last tree node is allocated, update bighint.
|
|
*/
|
|
if (scan_from_start && !(digit == BLIST_META_RADIX - 1 &&
|
|
scan[i].bm_bighint == BLIST_MAX_ALLOC))
|
|
scan->bm_bighint = *count - 1;
|
|
|
|
return (SWAPBLK_NONE);
|
|
}
|
|
|
|
/*
|
|
* BLST_LEAF_FREE() - free allocated block from leaf bitmap
|
|
*
|
|
*/
|
|
static void
|
|
blst_leaf_free(blmeta_t *scan, daddr_t blk, int count)
|
|
{
|
|
u_daddr_t mask;
|
|
|
|
/*
|
|
* free some data in this bitmap
|
|
* mask=0000111111111110000
|
|
* \_________/\__/
|
|
* count n
|
|
*/
|
|
mask = bitrange(blk & BLIST_BMAP_MASK, count);
|
|
KASSERT((scan->bm_bitmap & mask) == 0,
|
|
("freeing free block: %jx, size %d, mask %jx",
|
|
(uintmax_t)blk, count, (uintmax_t)scan->bm_bitmap & mask));
|
|
scan->bm_bitmap |= mask;
|
|
}
|
|
|
|
/*
|
|
* BLST_META_FREE() - free allocated blocks from radix tree meta info
|
|
*
|
|
* This support routine frees a range of blocks from the bitmap.
|
|
* The range must be entirely enclosed by this radix node. If a
|
|
* meta node, we break the range down recursively to free blocks
|
|
* in subnodes (which means that this code can free an arbitrary
|
|
* range whereas the allocation code cannot allocate an arbitrary
|
|
* range).
|
|
*/
|
|
static void
|
|
blst_meta_free(blmeta_t *scan, daddr_t freeBlk, daddr_t count, u_daddr_t radix)
|
|
{
|
|
daddr_t blk, endBlk, i, skip;
|
|
int digit, endDigit;
|
|
|
|
/*
|
|
* We could probably do a better job here. We are required to make
|
|
* bighint at least as large as the biggest allocable block of data.
|
|
* If we just shoehorn it, a little extra overhead will be incurred
|
|
* on the next allocation (but only that one typically).
|
|
*/
|
|
scan->bm_bighint = BLIST_MAX_ALLOC;
|
|
|
|
if (radix == BLIST_BMAP_RADIX)
|
|
return (blst_leaf_free(scan, freeBlk, count));
|
|
|
|
endBlk = ummin(freeBlk + count, (freeBlk + radix) & -radix);
|
|
radix /= BLIST_META_RADIX;
|
|
skip = radix_to_skip(radix);
|
|
blk = freeBlk & -radix;
|
|
digit = (blk / radix) & BLIST_META_MASK;
|
|
endDigit = 1 + (((endBlk - 1) / radix) & BLIST_META_MASK);
|
|
scan->bm_bitmap |= bitrange(digit, endDigit - digit);
|
|
for (i = 1 + digit * skip; blk < endBlk; i += skip) {
|
|
blk += radix;
|
|
count = ummin(blk, endBlk) - freeBlk;
|
|
blst_meta_free(&scan[i], freeBlk, count, radix);
|
|
freeBlk = blk;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* BLST_COPY() - copy one radix tree to another
|
|
*
|
|
* Locates free space in the source tree and frees it in the destination
|
|
* tree. The space may not already be free in the destination.
|
|
*/
|
|
static void
|
|
blst_copy(blmeta_t *scan, daddr_t blk, daddr_t radix, blist_t dest,
|
|
daddr_t count)
|
|
{
|
|
daddr_t endBlk, i, skip;
|
|
|
|
/*
|
|
* Leaf node
|
|
*/
|
|
|
|
if (radix == BLIST_BMAP_RADIX) {
|
|
u_daddr_t v = scan->bm_bitmap;
|
|
|
|
if (v == (u_daddr_t)-1) {
|
|
blist_free(dest, blk, count);
|
|
} else if (v != 0) {
|
|
int i;
|
|
|
|
for (i = 0; i < count; ++i) {
|
|
if (v & ((u_daddr_t)1 << i))
|
|
blist_free(dest, blk + i, 1);
|
|
}
|
|
}
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* Meta node
|
|
*/
|
|
|
|
if (scan->bm_bitmap == 0) {
|
|
/*
|
|
* Source all allocated, leave dest allocated
|
|
*/
|
|
return;
|
|
}
|
|
|
|
endBlk = blk + count;
|
|
radix /= BLIST_META_RADIX;
|
|
skip = radix_to_skip(radix);
|
|
for (i = 1; blk < endBlk; i += skip) {
|
|
blk += radix;
|
|
count = radix;
|
|
if (blk >= endBlk)
|
|
count -= blk - endBlk;
|
|
blst_copy(&scan[i], blk - radix, radix, dest, count);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* BLST_LEAF_FILL() - allocate specific blocks in leaf bitmap
|
|
*
|
|
* This routine allocates all blocks in the specified range
|
|
* regardless of any existing allocations in that range. Returns
|
|
* the number of blocks allocated by the call.
|
|
*/
|
|
static daddr_t
|
|
blst_leaf_fill(blmeta_t *scan, daddr_t blk, int count)
|
|
{
|
|
daddr_t nblks;
|
|
u_daddr_t mask;
|
|
|
|
mask = bitrange(blk & BLIST_BMAP_MASK, count);
|
|
|
|
/* Count the number of blocks that we are allocating. */
|
|
nblks = bitcount64(scan->bm_bitmap & mask);
|
|
|
|
scan->bm_bitmap &= ~mask;
|
|
return (nblks);
|
|
}
|
|
|
|
/*
|
|
* BLIST_META_FILL() - allocate specific blocks at a meta node
|
|
*
|
|
* This routine allocates the specified range of blocks,
|
|
* regardless of any existing allocations in the range. The
|
|
* range must be within the extent of this node. Returns the
|
|
* number of blocks allocated by the call.
|
|
*/
|
|
static daddr_t
|
|
blst_meta_fill(blmeta_t *scan, daddr_t allocBlk, daddr_t count, u_daddr_t radix)
|
|
{
|
|
daddr_t blk, endBlk, i, nblks, skip;
|
|
int digit;
|
|
|
|
if (radix == BLIST_BMAP_RADIX)
|
|
return (blst_leaf_fill(scan, allocBlk, count));
|
|
|
|
endBlk = ummin(allocBlk + count, (allocBlk + radix) & -radix);
|
|
radix /= BLIST_META_RADIX;
|
|
skip = radix_to_skip(radix);
|
|
blk = allocBlk & -radix;
|
|
nblks = 0;
|
|
while (blk < endBlk) {
|
|
digit = (blk / radix) & BLIST_META_MASK;
|
|
i = 1 + digit * skip;
|
|
blk += radix;
|
|
count = ummin(blk, endBlk) - allocBlk;
|
|
nblks += blst_meta_fill(&scan[i], allocBlk, count, radix);
|
|
if (scan[i].bm_bitmap == 0)
|
|
scan->bm_bitmap &= ~((u_daddr_t)1 << digit);
|
|
allocBlk = blk;
|
|
}
|
|
return (nblks);
|
|
}
|
|
|
|
#ifdef BLIST_DEBUG
|
|
|
|
static void
|
|
blst_radix_print(blmeta_t *scan, daddr_t blk, daddr_t radix, int tab)
|
|
{
|
|
daddr_t skip;
|
|
u_daddr_t mask;
|
|
int digit;
|
|
|
|
if (radix == BLIST_BMAP_RADIX) {
|
|
printf(
|
|
"%*.*s(%08llx,%lld): bitmap %0*llx big=%lld\n",
|
|
tab, tab, "",
|
|
(long long)blk, (long long)radix,
|
|
1 + (BLIST_BMAP_RADIX - 1) / 4,
|
|
(long long)scan->bm_bitmap,
|
|
(long long)scan->bm_bighint
|
|
);
|
|
return;
|
|
}
|
|
|
|
printf(
|
|
"%*.*s(%08llx): subtree (%lld/%lld) bitmap %0*llx big=%lld {\n",
|
|
tab, tab, "",
|
|
(long long)blk, (long long)radix,
|
|
(long long)radix,
|
|
1 + (BLIST_META_RADIX - 1) / 4,
|
|
(long long)scan->bm_bitmap,
|
|
(long long)scan->bm_bighint
|
|
);
|
|
|
|
radix /= BLIST_META_RADIX;
|
|
skip = radix_to_skip(radix);
|
|
tab += 4;
|
|
|
|
mask = scan->bm_bitmap;
|
|
/* Examine the nonempty subtree associated with each bit set in mask */
|
|
do {
|
|
digit = bitpos(mask);
|
|
blst_radix_print(&scan[1 + digit * skip], blk + digit * radix,
|
|
radix, tab);
|
|
} while ((mask ^= bitrange(digit, 1)) != 0);
|
|
tab -= 4;
|
|
|
|
printf(
|
|
"%*.*s}\n",
|
|
tab, tab, ""
|
|
);
|
|
}
|
|
|
|
#endif
|
|
|
|
#ifdef BLIST_DEBUG
|
|
|
|
int
|
|
main(int ac, char **av)
|
|
{
|
|
int size = BLIST_META_RADIX * BLIST_BMAP_RADIX;
|
|
int i;
|
|
blist_t bl;
|
|
struct sbuf *s;
|
|
|
|
for (i = 1; i < ac; ++i) {
|
|
const char *ptr = av[i];
|
|
if (*ptr != '-') {
|
|
size = strtol(ptr, NULL, 0);
|
|
continue;
|
|
}
|
|
ptr += 2;
|
|
fprintf(stderr, "Bad option: %s\n", ptr - 2);
|
|
exit(1);
|
|
}
|
|
bl = blist_create(size, M_WAITOK);
|
|
blist_free(bl, 0, size);
|
|
|
|
for (;;) {
|
|
char buf[1024];
|
|
long long da = 0;
|
|
int count = 0, maxcount = 0;
|
|
|
|
printf("%lld/%lld/%lld> ", (long long)blist_avail(bl),
|
|
(long long)size, (long long)bl->bl_radix);
|
|
fflush(stdout);
|
|
if (fgets(buf, sizeof(buf), stdin) == NULL)
|
|
break;
|
|
switch(buf[0]) {
|
|
case 'r':
|
|
if (sscanf(buf + 1, "%d", &count) == 1) {
|
|
blist_resize(&bl, count, 1, M_WAITOK);
|
|
} else {
|
|
printf("?\n");
|
|
}
|
|
case 'p':
|
|
blist_print(bl);
|
|
break;
|
|
case 's':
|
|
s = sbuf_new_auto();
|
|
blist_stats(bl, s);
|
|
sbuf_finish(s);
|
|
printf("%s", sbuf_data(s));
|
|
sbuf_delete(s);
|
|
break;
|
|
case 'a':
|
|
if (sscanf(buf + 1, "%d%d", &count, &maxcount) == 2) {
|
|
daddr_t blk = blist_alloc(bl, &count, maxcount);
|
|
printf(" R=%08llx, c=%08d\n",
|
|
(long long)blk, count);
|
|
} else {
|
|
printf("?\n");
|
|
}
|
|
break;
|
|
case 'f':
|
|
if (sscanf(buf + 1, "%llx %d", &da, &count) == 2) {
|
|
blist_free(bl, da, count);
|
|
} else {
|
|
printf("?\n");
|
|
}
|
|
break;
|
|
case 'l':
|
|
if (sscanf(buf + 1, "%llx %d", &da, &count) == 2) {
|
|
printf(" n=%jd\n",
|
|
(intmax_t)blist_fill(bl, da, count));
|
|
} else {
|
|
printf("?\n");
|
|
}
|
|
break;
|
|
case '?':
|
|
case 'h':
|
|
puts(
|
|
"p -print\n"
|
|
"s -stats\n"
|
|
"a %d %d -allocate\n"
|
|
"f %x %d -free\n"
|
|
"l %x %d -fill\n"
|
|
"r %d -resize\n"
|
|
"h/? -help\n"
|
|
"q -quit"
|
|
);
|
|
break;
|
|
case 'q':
|
|
break;
|
|
default:
|
|
printf("?\n");
|
|
break;
|
|
}
|
|
if (buf[0] == 'q')
|
|
break;
|
|
}
|
|
return (0);
|
|
}
|
|
|
|
#endif
|