cursor lies in the middle of the space that the meta node represents, then blanking the low bits of mask may make it zero, and break later code that expects a nonzero value. Add a test that returns failure if the mask has been cleared. Submitted by: Doug Moore <dougm@rice.edu> Reported by: pho Tested by: pho X-MFC with: r340402 Differential Revision: https://reviews.freebsd.org/D18058
1147 lines
30 KiB
C
1147 lines
30 KiB
C
/*-
|
|
* 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
|
|
* 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
|
|
* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
|
|
* notice, this list of conditions and the following disclaimer in the
|
|
* 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
|
|
* 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
|
|
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
|
|
* GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
|
|
* 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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|
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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 <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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#include <sys/blist.h>
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void panic(const char *ctl, ...);
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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, int count);
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static daddr_t blst_meta_alloc(blmeta_t *scan, daddr_t cursor, daddr_t count,
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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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|
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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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|
/*
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|
* Use binary search, or a faster method, to find the 1 bit in a u_daddr_t.
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* Assumes that the argument has only one bit set.
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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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|
int hi, lo, mid;
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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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|
default:
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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 >> mid) != 0)
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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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|
return (lo);
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|
}
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|
}
|
|
|
|
/*
|
|
* blist_create() - create a blist capable of handling up to the specified
|
|
* number of blocks
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|
*
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|
* blocks - must be greater than 0
|
|
* flags - malloc flags
|
|
*
|
|
* The smallest blist consists of a single leaf node capable of
|
|
* managing BLIST_BMAP_RADIX blocks.
|
|
*/
|
|
blist_t
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|
blist_create(daddr_t blocks, int flags)
|
|
{
|
|
blist_t bl;
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|
u_daddr_t nodes, radix;
|
|
|
|
if (blocks == 0)
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|
panic("invalid block count");
|
|
|
|
/*
|
|
* Calculate the radix and node count used for scanning.
|
|
*/
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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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|
}
|
|
|
|
bl = malloc(offsetof(struct blist, bl_root[nodes]), M_SWAP, flags |
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|
M_ZERO);
|
|
if (bl == NULL)
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|
return (NULL);
|
|
|
|
bl->bl_blocks = blocks;
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|
bl->bl_radix = radix;
|
|
|
|
#if defined(BLIST_DEBUG)
|
|
printf(
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|
"BLIST representing %lld blocks (%lld MB of swap)"
|
|
", requiring %lldK of ram\n",
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|
(long long)bl->bl_blocks,
|
|
(long long)bl->bl_blocks * 4 / 1024,
|
|
(long long)(nodes * sizeof(blmeta_t) + 1023) / 1024
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|
);
|
|
printf("BLIST raw radix tree contains %lld records\n",
|
|
(long long)nodes);
|
|
#endif
|
|
|
|
return (bl);
|
|
}
|
|
|
|
void
|
|
blist_destroy(blist_t bl)
|
|
{
|
|
|
|
free(bl, M_SWAP);
|
|
}
|
|
|
|
/*
|
|
* blist_alloc() - reserve space in the block bitmap. Return the base
|
|
* of a contiguous region or SWAPBLK_NONE if space could
|
|
* not be allocated.
|
|
*/
|
|
daddr_t
|
|
blist_alloc(blist_t bl, daddr_t count)
|
|
{
|
|
daddr_t blk;
|
|
|
|
if (count > BLIST_MAX_ALLOC)
|
|
panic("allocation too large");
|
|
|
|
/*
|
|
* This loop iterates at most twice. An allocation failure in the
|
|
* first iteration leads to a second iteration only if the cursor was
|
|
* non-zero. When the cursor is zero, an allocation failure will
|
|
* reduce the hint, stopping further iterations.
|
|
*/
|
|
while (count <= bl->bl_root->bm_bighint) {
|
|
blk = blst_meta_alloc(bl->bl_root, bl->bl_cursor, count,
|
|
bl->bl_radix);
|
|
if (blk != SWAPBLK_NONE) {
|
|
bl->bl_avail -= count;
|
|
bl->bl_cursor = blk + count;
|
|
if (bl->bl_cursor == bl->bl_blocks)
|
|
bl->bl_cursor = 0;
|
|
return (blk);
|
|
}
|
|
bl->bl_cursor = 0;
|
|
}
|
|
return (SWAPBLK_NONE);
|
|
}
|
|
|
|
/*
|
|
* blist_avail() - return the number of free blocks.
|
|
*/
|
|
daddr_t
|
|
blist_avail(blist_t bl)
|
|
{
|
|
|
|
return (bl->bl_avail);
|
|
}
|
|
|
|
/*
|
|
* blist_free() - free up space in the block bitmap. Return the base
|
|
* of a contiguous region. Panic if an inconsistancy is
|
|
* found.
|
|
*/
|
|
void
|
|
blist_free(blist_t bl, daddr_t blkno, daddr_t count)
|
|
{
|
|
|
|
if (blkno < 0 || blkno + count > bl->bl_blocks)
|
|
panic("freeing invalid range");
|
|
blst_meta_free(bl->bl_root, blkno, count, bl->bl_radix);
|
|
bl->bl_avail += count;
|
|
}
|
|
|
|
/*
|
|
* blist_fill() - mark a region in the block bitmap as off-limits
|
|
* to the allocator (i.e. allocate it), ignoring any
|
|
* existing allocations. Return the number of blocks
|
|
* actually filled that were free before the call.
|
|
*/
|
|
daddr_t
|
|
blist_fill(blist_t bl, daddr_t blkno, daddr_t count)
|
|
{
|
|
daddr_t filled;
|
|
|
|
if (blkno < 0 || blkno + count > bl->bl_blocks)
|
|
panic("filling invalid range");
|
|
filled = blst_meta_fill(bl->bl_root, blkno, count, bl->bl_radix);
|
|
bl->bl_avail -= filled;
|
|
return (filled);
|
|
}
|
|
|
|
/*
|
|
* blist_resize() - resize an existing radix tree to handle the
|
|
* specified number of blocks. This will reallocate
|
|
* the tree and transfer the previous bitmap to the new
|
|
* one. When extending the tree you can specify whether
|
|
* the new blocks are to left allocated or freed.
|
|
*/
|
|
void
|
|
blist_resize(blist_t *pbl, daddr_t count, int freenew, int flags)
|
|
{
|
|
blist_t newbl = blist_create(count, flags);
|
|
blist_t save = *pbl;
|
|
|
|
*pbl = newbl;
|
|
if (count > save->bl_blocks)
|
|
count = save->bl_blocks;
|
|
blst_copy(save->bl_root, 0, save->bl_radix, newbl, count);
|
|
|
|
/*
|
|
* If resizing upwards, should we free the new space or not?
|
|
*/
|
|
if (freenew && count < newbl->bl_blocks) {
|
|
blist_free(newbl, count, newbl->bl_blocks - count);
|
|
}
|
|
blist_destroy(save);
|
|
}
|
|
|
|
#ifdef BLIST_DEBUG
|
|
|
|
/*
|
|
* blist_print() - dump radix tree
|
|
*/
|
|
void
|
|
blist_print(blist_t bl)
|
|
{
|
|
printf("BLIST avail = %jd, cursor = %08jx {\n",
|
|
(uintmax_t)bl->bl_avail, (uintmax_t)bl->bl_cursor);
|
|
|
|
if (bl->bl_root->bm_bitmap != 0)
|
|
blst_radix_print(bl->bl_root, 0, bl->bl_radix, 4);
|
|
printf("}\n");
|
|
}
|
|
|
|
#endif
|
|
|
|
static const u_daddr_t fib[] = {
|
|
1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377, 610, 987, 1597, 2584,
|
|
4181, 6765, 10946, 17711, 28657, 46368, 75025, 121393, 196418, 317811,
|
|
514229, 832040, 1346269, 2178309, 3524578,
|
|
};
|
|
|
|
/*
|
|
* Use 'gap' to describe a maximal range of unallocated blocks/bits.
|
|
*/
|
|
struct gap_stats {
|
|
daddr_t start; /* current gap start, or SWAPBLK_NONE */
|
|
daddr_t num; /* number of gaps observed */
|
|
daddr_t max; /* largest gap size */
|
|
daddr_t avg; /* average gap size */
|
|
daddr_t err; /* sum - num * avg */
|
|
daddr_t histo[nitems(fib)]; /* # gaps in each size range */
|
|
int max_bucket; /* last histo elt with nonzero val */
|
|
};
|
|
|
|
/*
|
|
* gap_stats_counting() - is the state 'counting 1 bits'?
|
|
* or 'skipping 0 bits'?
|
|
*/
|
|
static inline bool
|
|
gap_stats_counting(const struct gap_stats *stats)
|
|
{
|
|
|
|
return (stats->start != SWAPBLK_NONE);
|
|
}
|
|
|
|
/*
|
|
* init_gap_stats() - initialize stats on gap sizes
|
|
*/
|
|
static inline void
|
|
init_gap_stats(struct gap_stats *stats)
|
|
{
|
|
|
|
bzero(stats, sizeof(*stats));
|
|
stats->start = SWAPBLK_NONE;
|
|
}
|
|
|
|
/*
|
|
* update_gap_stats() - update stats on gap sizes
|
|
*/
|
|
static void
|
|
update_gap_stats(struct gap_stats *stats, daddr_t posn)
|
|
{
|
|
daddr_t size;
|
|
int hi, lo, mid;
|
|
|
|
if (!gap_stats_counting(stats)) {
|
|
stats->start = posn;
|
|
return;
|
|
}
|
|
size = posn - stats->start;
|
|
stats->start = SWAPBLK_NONE;
|
|
if (size > stats->max)
|
|
stats->max = size;
|
|
|
|
/*
|
|
* Find the fibonacci range that contains size,
|
|
* expecting to find it in an early range.
|
|
*/
|
|
lo = 0;
|
|
hi = 1;
|
|
while (hi < nitems(fib) && fib[hi] <= size) {
|
|
lo = hi;
|
|
hi *= 2;
|
|
}
|
|
if (hi >= nitems(fib))
|
|
hi = nitems(fib);
|
|
while (lo + 1 != hi) {
|
|
mid = (lo + hi) >> 1;
|
|
if (fib[mid] <= size)
|
|
lo = mid;
|
|
else
|
|
hi = mid;
|
|
}
|
|
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 bit, diff, mask;
|
|
|
|
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) {
|
|
bit = diff & -diff;
|
|
update_gap_stats(stats, i + bitpos(bit));
|
|
diff ^= bit;
|
|
}
|
|
}
|
|
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 first few blocks in the next leaf.
|
|
*
|
|
* 'scan' is a leaf node, associated with a block containing 'blk'.
|
|
* 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 'blk' to determine how many meta-nodes lie between the
|
|
* leaves. If the next leaf 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 blk, int count)
|
|
{
|
|
blmeta_t *next;
|
|
daddr_t skip;
|
|
u_daddr_t radix;
|
|
int digit;
|
|
|
|
next = scan + 1;
|
|
blk += BLIST_BMAP_RADIX;
|
|
radix = BLIST_BMAP_RADIX;
|
|
while ((digit = ((blk / radix) & BLIST_META_MASK)) == 0 &&
|
|
(next->bm_bitmap & 1) == 1) {
|
|
next++;
|
|
radix *= BLIST_META_RADIX;
|
|
}
|
|
if (((next->bm_bitmap + 1) & ~((u_daddr_t)-1 << count)) != 0) {
|
|
/*
|
|
* The next leaf doesn't have enough free blocks at the
|
|
* beginning to complete the spanning allocation.
|
|
*/
|
|
return (ENOMEM);
|
|
}
|
|
/* Clear the first 'count' bits in the next leaf to allocate. */
|
|
next->bm_bitmap &= (u_daddr_t)-1 << count;
|
|
|
|
/*
|
|
* Update bitmaps of next-ancestors, up to least common ancestor.
|
|
*/
|
|
skip = radix_to_skip(radix);
|
|
while (radix != BLIST_BMAP_RADIX && next->bm_bitmap == 0) {
|
|
(--next)->bm_bitmap ^= 1;
|
|
radix /= BLIST_META_RADIX;
|
|
}
|
|
if (next->bm_bitmap == 0)
|
|
scan[-digit * skip].bm_bitmap ^= (u_daddr_t)1 << digit;
|
|
return (0);
|
|
}
|
|
|
|
/*
|
|
* BLST_LEAF_ALLOC() - allocate at a leaf in the radix tree (a bitmap).
|
|
*
|
|
* This is the core of the allocator and is optimized for the
|
|
* BLIST_BMAP_RADIX block allocation case. Otherwise, execution
|
|
* time is proportional to log2(count) + bitpos time.
|
|
*/
|
|
static daddr_t
|
|
blst_leaf_alloc(blmeta_t *scan, daddr_t blk, int count)
|
|
{
|
|
u_daddr_t mask;
|
|
int count1, hi, lo, num_shifts, range1, range_ext;
|
|
|
|
range1 = 0;
|
|
count1 = count - 1;
|
|
num_shifts = fls(count1);
|
|
mask = scan->bm_bitmap;
|
|
while ((-mask & ~mask) != 0 && num_shifts > 0) {
|
|
/*
|
|
* If bit i is set in mask, then bits in [i, i+range1] are set
|
|
* in scan->bm_bitmap. The value of range1 is equal to
|
|
* count1 >> num_shifts. Grow range and reduce num_shifts to 0,
|
|
* while preserving these invariants. The updates to mask leave
|
|
* fewer bits set, but each bit that remains set represents a
|
|
* longer string of consecutive bits set in scan->bm_bitmap.
|
|
* If more updates to mask cannot clear more bits, because mask
|
|
* is partitioned with all 0 bits preceding all 1 bits, the loop
|
|
* terminates immediately.
|
|
*/
|
|
num_shifts--;
|
|
range_ext = range1 + ((count1 >> num_shifts) & 1);
|
|
/*
|
|
* mask is a signed quantity for the shift because when it is
|
|
* shifted right, the sign bit should copied; when the last
|
|
* block of the leaf is free, pretend, for a while, that all the
|
|
* blocks that follow it are also free.
|
|
*/
|
|
mask &= (daddr_t)mask >> range_ext;
|
|
range1 += range_ext;
|
|
}
|
|
if (mask == 0) {
|
|
/*
|
|
* Update bighint. There is no allocation bigger than range1
|
|
* starting in this leaf.
|
|
*/
|
|
scan->bm_bighint = range1;
|
|
return (SWAPBLK_NONE);
|
|
}
|
|
|
|
/* Discard any candidates that appear before blk. */
|
|
mask &= (u_daddr_t)-1 << (blk & BLIST_BMAP_MASK);
|
|
if (mask == 0)
|
|
return (SWAPBLK_NONE);
|
|
|
|
/*
|
|
* The least significant set bit in mask marks the start of the first
|
|
* available range of sufficient size. Clear all the bits but that one,
|
|
* and then find its position.
|
|
*/
|
|
mask &= -mask;
|
|
lo = bitpos(mask);
|
|
|
|
hi = lo + count;
|
|
if (hi > BLIST_BMAP_RADIX) {
|
|
/*
|
|
* An allocation within this leaf is impossible, so a successful
|
|
* allocation depends on the next leaf providing some of the blocks.
|
|
*/
|
|
if (blst_next_leaf_alloc(scan, blk, hi - BLIST_BMAP_RADIX) != 0)
|
|
/*
|
|
* 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);
|
|
hi = BLIST_BMAP_RADIX;
|
|
}
|
|
|
|
/* Set the bits of mask at position 'lo' and higher. */
|
|
mask = -mask;
|
|
if (hi == BLIST_BMAP_RADIX) {
|
|
/*
|
|
* Update bighint. There is no allocation bigger than range1
|
|
* available in this leaf after this allocation completes.
|
|
*/
|
|
scan->bm_bighint = range1;
|
|
} else {
|
|
/* Clear the bits of mask at position 'hi' and higher. */
|
|
mask &= (u_daddr_t)-1 >> (BLIST_BMAP_RADIX - hi);
|
|
}
|
|
/* Clear the allocated bits from this leaf. */
|
|
scan->bm_bitmap &= ~mask;
|
|
return ((blk & ~BLIST_BMAP_MASK) + 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, daddr_t count, u_daddr_t radix)
|
|
{
|
|
daddr_t blk, i, r, skip;
|
|
u_daddr_t bit, mask;
|
|
bool scan_from_start;
|
|
int digit;
|
|
|
|
if (radix == BLIST_BMAP_RADIX)
|
|
return (blst_leaf_alloc(scan, cursor, count));
|
|
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 {
|
|
bit = mask & -mask;
|
|
digit = bitpos(bit);
|
|
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, radix);
|
|
if (r != SWAPBLK_NONE) {
|
|
if (scan[i].bm_bitmap == 0)
|
|
scan->bm_bitmap ^= bit;
|
|
return (r);
|
|
}
|
|
}
|
|
cursor = blk;
|
|
} while ((mask ^= bit) != 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);
|
|
if (scan->bm_bitmap & mask)
|
|
panic("freeing free block");
|
|
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 bit, 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 {
|
|
bit = mask & -mask;
|
|
digit = bitpos(bit);
|
|
blst_radix_print(&scan[1 + digit * skip], blk + digit * radix,
|
|
radix, tab);
|
|
} while ((mask ^= bit) != 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;
|
|
long long count = 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, "%lld", &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, "%lld", &count) == 1) {
|
|
daddr_t blk = blist_alloc(bl, count);
|
|
printf(" R=%08llx\n", (long long)blk);
|
|
} else {
|
|
printf("?\n");
|
|
}
|
|
break;
|
|
case 'f':
|
|
if (sscanf(buf + 1, "%llx %lld", &da, &count) == 2) {
|
|
blist_free(bl, da, count);
|
|
} else {
|
|
printf("?\n");
|
|
}
|
|
break;
|
|
case 'l':
|
|
if (sscanf(buf + 1, "%llx %lld", &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 -allocate\n"
|
|
"f %x %d -free\n"
|
|
"l %x %d -fill\n"
|
|
"r %d -resize\n"
|
|
"h/? -help"
|
|
);
|
|
break;
|
|
default:
|
|
printf("?\n");
|
|
break;
|
|
}
|
|
}
|
|
return(0);
|
|
}
|
|
|
|
void
|
|
panic(const char *ctl, ...)
|
|
{
|
|
va_list va;
|
|
|
|
va_start(va, ctl);
|
|
vfprintf(stderr, ctl, va);
|
|
fprintf(stderr, "\n");
|
|
va_end(va);
|
|
exit(1);
|
|
}
|
|
|
|
#endif
|