458 lines
16 KiB
C
458 lines
16 KiB
C
/*-
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* Copyright (c) 2002-2005, 2009 Jeffrey Roberson <jeff@FreeBSD.org>
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* Copyright (c) 2004, 2005 Bosko Milekic <bmilekic@FreeBSD.org>
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* All rights reserved.
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*
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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 unmodified, this list of conditions, and the following
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* 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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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* $FreeBSD$
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*
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*/
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/*
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* This file includes definitions, structures, prototypes, and inlines that
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* should not be used outside of the actual implementation of UMA.
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*/
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/*
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* Here's a quick description of the relationship between the objects:
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*
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* Kegs contain lists of slabs which are stored in either the full bin, empty
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* bin, or partially allocated bin, to reduce fragmentation. They also contain
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* the user supplied value for size, which is adjusted for alignment purposes
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* and rsize is the result of that. The Keg also stores information for
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* managing a hash of page addresses that maps pages to uma_slab_t structures
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* for pages that don't have embedded uma_slab_t's.
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*
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* The uma_slab_t may be embedded in a UMA_SLAB_SIZE chunk of memory or it may
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* be allocated off the page from a special slab zone. The free list within a
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* slab is managed with a linked list of indices, which are 8 bit values. If
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* UMA_SLAB_SIZE is defined to be too large I will have to switch to 16bit
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* values. Currently on alpha you can get 250 or so 32 byte items and on x86
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* you can get 250 or so 16byte items. For item sizes that would yield more
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* than 10% memory waste we potentially allocate a separate uma_slab_t if this
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* will improve the number of items per slab that will fit.
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*
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* Other potential space optimizations are storing the 8bit of linkage in space
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* wasted between items due to alignment problems. This may yield a much better
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* memory footprint for certain sizes of objects. Another alternative is to
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* increase the UMA_SLAB_SIZE, or allow for dynamic slab sizes. I prefer
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* dynamic slab sizes because we could stick with 8 bit indices and only use
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* large slab sizes for zones with a lot of waste per slab. This may create
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* inefficiencies in the vm subsystem due to fragmentation in the address space.
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*
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* The only really gross cases, with regards to memory waste, are for those
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* items that are just over half the page size. You can get nearly 50% waste,
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* so you fall back to the memory footprint of the power of two allocator. I
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* have looked at memory allocation sizes on many of the machines available to
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* me, and there does not seem to be an abundance of allocations at this range
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* so at this time it may not make sense to optimize for it. This can, of
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* course, be solved with dynamic slab sizes.
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*
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* Kegs may serve multiple Zones but by far most of the time they only serve
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* one. When a Zone is created, a Keg is allocated and setup for it. While
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* the backing Keg stores slabs, the Zone caches Buckets of items allocated
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* from the slabs. Each Zone is equipped with an init/fini and ctor/dtor
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* pair, as well as with its own set of small per-CPU caches, layered above
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* the Zone's general Bucket cache.
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*
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* The PCPU caches are protected by critical sections, and may be accessed
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* safely only from their associated CPU, while the Zones backed by the same
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* Keg all share a common Keg lock (to coalesce contention on the backing
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* slabs). The backing Keg typically only serves one Zone but in the case of
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* multiple Zones, one of the Zones is considered the Master Zone and all
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* Zone-related stats from the Keg are done in the Master Zone. For an
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* example of a Multi-Zone setup, refer to the Mbuf allocation code.
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*/
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/*
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* This is the representation for normal (Non OFFPAGE slab)
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*
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* i == item
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* s == slab pointer
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*
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* <---------------- Page (UMA_SLAB_SIZE) ------------------>
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* ___________________________________________________________
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* | _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ ___________ |
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* ||i||i||i||i||i||i||i||i||i||i||i||i||i||i||i| |slab header||
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* ||_||_||_||_||_||_||_||_||_||_||_||_||_||_||_| |___________||
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* |___________________________________________________________|
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*
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*
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* This is an OFFPAGE slab. These can be larger than UMA_SLAB_SIZE.
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*
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* ___________________________________________________________
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* | _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ |
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* ||i||i||i||i||i||i||i||i||i||i||i||i||i||i||i||i||i||i||i| |
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* ||_||_||_||_||_||_||_||_||_||_||_||_||_||_||_||_||_||_||_| |
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* |___________________________________________________________|
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* ___________ ^
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* |slab header| |
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* |___________|---*
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*
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*/
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#ifndef VM_UMA_INT_H
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#define VM_UMA_INT_H
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#define UMA_SLAB_SIZE PAGE_SIZE /* How big are our slabs? */
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#define UMA_SLAB_MASK (PAGE_SIZE - 1) /* Mask to get back to the page */
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#define UMA_SLAB_SHIFT PAGE_SHIFT /* Number of bits PAGE_MASK */
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#define UMA_BOOT_PAGES 64 /* Pages allocated for startup */
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/* Max waste percentage before going to off page slab management */
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#define UMA_MAX_WASTE 10
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/*
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* I doubt there will be many cases where this is exceeded. This is the initial
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* size of the hash table for uma_slabs that are managed off page. This hash
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* does expand by powers of two. Currently it doesn't get smaller.
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*/
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#define UMA_HASH_SIZE_INIT 32
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/*
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* I should investigate other hashing algorithms. This should yield a low
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* number of collisions if the pages are relatively contiguous.
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*
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* This is the same algorithm that most processor caches use.
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*
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* I'm shifting and masking instead of % because it should be faster.
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*/
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#define UMA_HASH(h, s) ((((unsigned long)s) >> UMA_SLAB_SHIFT) & \
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(h)->uh_hashmask)
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#define UMA_HASH_INSERT(h, s, mem) \
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SLIST_INSERT_HEAD(&(h)->uh_slab_hash[UMA_HASH((h), \
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(mem))], (s), us_hlink)
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#define UMA_HASH_REMOVE(h, s, mem) \
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SLIST_REMOVE(&(h)->uh_slab_hash[UMA_HASH((h), \
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(mem))], (s), uma_slab, us_hlink)
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/* Hash table for freed address -> slab translation */
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SLIST_HEAD(slabhead, uma_slab);
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struct uma_hash {
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struct slabhead *uh_slab_hash; /* Hash table for slabs */
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int uh_hashsize; /* Current size of the hash table */
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int uh_hashmask; /* Mask used during hashing */
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};
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/*
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* align field or structure to cache line
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*/
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#if defined(__amd64__)
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#define UMA_ALIGN __aligned(CACHE_LINE_SIZE)
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#else
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#define UMA_ALIGN
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#endif
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/*
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* Structures for per cpu queues.
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*/
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struct uma_bucket {
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LIST_ENTRY(uma_bucket) ub_link; /* Link into the zone */
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int16_t ub_cnt; /* Count of free items. */
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int16_t ub_entries; /* Max items. */
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void *ub_bucket[]; /* actual allocation storage */
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};
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typedef struct uma_bucket * uma_bucket_t;
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struct uma_cache {
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uma_bucket_t uc_freebucket; /* Bucket we're freeing to */
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uma_bucket_t uc_allocbucket; /* Bucket to allocate from */
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u_int64_t uc_allocs; /* Count of allocations */
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u_int64_t uc_frees; /* Count of frees */
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} UMA_ALIGN;
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typedef struct uma_cache * uma_cache_t;
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/*
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* Keg management structure
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*
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* TODO: Optimize for cache line size
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*
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*/
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struct uma_keg {
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struct mtx uk_lock; /* Lock for the keg */
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struct uma_hash uk_hash;
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LIST_HEAD(,uma_zone) uk_zones; /* Keg's zones */
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LIST_HEAD(,uma_slab) uk_part_slab; /* partially allocated slabs */
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LIST_HEAD(,uma_slab) uk_free_slab; /* empty slab list */
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LIST_HEAD(,uma_slab) uk_full_slab; /* full slabs */
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u_int32_t uk_recurse; /* Allocation recursion count */
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u_int32_t uk_align; /* Alignment mask */
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u_int32_t uk_pages; /* Total page count */
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u_int32_t uk_free; /* Count of items free in slabs */
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u_int32_t uk_size; /* Requested size of each item */
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u_int32_t uk_rsize; /* Real size of each item */
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u_int32_t uk_maxpages; /* Maximum number of pages to alloc */
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uma_init uk_init; /* Keg's init routine */
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uma_fini uk_fini; /* Keg's fini routine */
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uma_alloc uk_allocf; /* Allocation function */
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uma_free uk_freef; /* Free routine */
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u_long uk_offset; /* Next free offset from base KVA */
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vm_offset_t uk_kva; /* Zone base KVA */
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uma_zone_t uk_slabzone; /* Slab zone backing us, if OFFPAGE */
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u_int16_t uk_slabsize; /* Slab size for this keg */
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u_int16_t uk_pgoff; /* Offset to uma_slab struct */
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u_int16_t uk_ppera; /* pages per allocation from backend */
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u_int16_t uk_ipers; /* Items per slab */
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u_int32_t uk_flags; /* Internal flags */
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/* Least used fields go to the last cache line. */
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const char *uk_name; /* Name of creating zone. */
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LIST_ENTRY(uma_keg) uk_link; /* List of all kegs */
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};
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typedef struct uma_keg * uma_keg_t;
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/* Page management structure */
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/* Sorry for the union, but space efficiency is important */
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struct uma_slab_head {
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uma_keg_t us_keg; /* Keg we live in */
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union {
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LIST_ENTRY(uma_slab) _us_link; /* slabs in zone */
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unsigned long _us_size; /* Size of allocation */
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} us_type;
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SLIST_ENTRY(uma_slab) us_hlink; /* Link for hash table */
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u_int8_t *us_data; /* First item */
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u_int16_t us_freecount; /* How many are free? */
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u_int8_t us_flags; /* Page flags see uma.h */
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u_int8_t us_firstfree; /* First free item index */
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};
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/* The standard slab structure */
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struct uma_slab {
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struct uma_slab_head us_head; /* slab header data */
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struct {
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u_int8_t us_item;
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} us_freelist[1]; /* actual number bigger */
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};
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/*
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* The slab structure for UMA_ZONE_REFCNT zones for whose items we
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* maintain reference counters in the slab for.
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*/
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struct uma_slab_refcnt {
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struct uma_slab_head us_head; /* slab header data */
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struct {
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u_int8_t us_item;
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u_int32_t us_refcnt;
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} us_freelist[1]; /* actual number bigger */
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};
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#define us_keg us_head.us_keg
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#define us_link us_head.us_type._us_link
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#define us_size us_head.us_type._us_size
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#define us_hlink us_head.us_hlink
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#define us_data us_head.us_data
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#define us_flags us_head.us_flags
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#define us_freecount us_head.us_freecount
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#define us_firstfree us_head.us_firstfree
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typedef struct uma_slab * uma_slab_t;
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typedef struct uma_slab_refcnt * uma_slabrefcnt_t;
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typedef uma_slab_t (*uma_slaballoc)(uma_zone_t, uma_keg_t, int);
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/*
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* These give us the size of one free item reference within our corresponding
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* uma_slab structures, so that our calculations during zone setup are correct
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* regardless of what the compiler decides to do with padding the structure
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* arrays within uma_slab.
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*/
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#define UMA_FRITM_SZ (sizeof(struct uma_slab) - sizeof(struct uma_slab_head))
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#define UMA_FRITMREF_SZ (sizeof(struct uma_slab_refcnt) - \
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sizeof(struct uma_slab_head))
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struct uma_klink {
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LIST_ENTRY(uma_klink) kl_link;
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uma_keg_t kl_keg;
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};
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typedef struct uma_klink *uma_klink_t;
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/*
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* Zone management structure
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*
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* TODO: Optimize for cache line size
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*
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*/
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struct uma_zone {
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const char *uz_name; /* Text name of the zone */
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struct mtx *uz_lock; /* Lock for the zone (keg's lock) */
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LIST_ENTRY(uma_zone) uz_link; /* List of all zones in keg */
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LIST_HEAD(,uma_bucket) uz_full_bucket; /* full buckets */
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LIST_HEAD(,uma_bucket) uz_free_bucket; /* Buckets for frees */
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LIST_HEAD(,uma_klink) uz_kegs; /* List of kegs. */
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struct uma_klink uz_klink; /* klink for first keg. */
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uma_slaballoc uz_slab; /* Allocate a slab from the backend. */
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uma_ctor uz_ctor; /* Constructor for each allocation */
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uma_dtor uz_dtor; /* Destructor */
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uma_init uz_init; /* Initializer for each item */
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uma_fini uz_fini; /* Discards memory */
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u_int32_t uz_flags; /* Flags inherited from kegs */
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u_int32_t uz_size; /* Size inherited from kegs */
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u_int64_t uz_allocs UMA_ALIGN; /* Total number of allocations */
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u_int64_t uz_frees; /* Total number of frees */
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u_int64_t uz_fails; /* Total number of alloc failures */
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u_int64_t uz_sleeps; /* Total number of alloc sleeps */
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uint16_t uz_fills; /* Outstanding bucket fills */
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uint16_t uz_count; /* Highest amount of items in bucket */
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/* The next three fields are used to print a rate-limited warnings. */
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const char *uz_warning; /* Warning to print on failure */
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struct timeval uz_ratecheck; /* Warnings rate-limiting */
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/*
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* This HAS to be the last item because we adjust the zone size
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* based on NCPU and then allocate the space for the zones.
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*/
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struct uma_cache uz_cpu[1]; /* Per cpu caches */
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};
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/*
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* These flags must not overlap with the UMA_ZONE flags specified in uma.h.
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*/
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#define UMA_ZFLAG_BUCKET 0x02000000 /* Bucket zone. */
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#define UMA_ZFLAG_MULTI 0x04000000 /* Multiple kegs in the zone. */
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#define UMA_ZFLAG_DRAINING 0x08000000 /* Running zone_drain. */
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#define UMA_ZFLAG_PRIVALLOC 0x10000000 /* Use uz_allocf. */
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#define UMA_ZFLAG_INTERNAL 0x20000000 /* No offpage no PCPU. */
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#define UMA_ZFLAG_FULL 0x40000000 /* Reached uz_maxpages */
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#define UMA_ZFLAG_CACHEONLY 0x80000000 /* Don't ask VM for buckets. */
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#define UMA_ZFLAG_INHERIT (UMA_ZFLAG_INTERNAL | UMA_ZFLAG_CACHEONLY | \
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UMA_ZFLAG_BUCKET)
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#undef UMA_ALIGN
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#ifdef _KERNEL
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/* Internal prototypes */
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static __inline uma_slab_t hash_sfind(struct uma_hash *hash, u_int8_t *data);
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void *uma_large_malloc(int size, int wait);
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void uma_large_free(uma_slab_t slab);
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/* Lock Macros */
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#define KEG_LOCK_INIT(k, lc) \
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do { \
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if ((lc)) \
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mtx_init(&(k)->uk_lock, (k)->uk_name, \
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(k)->uk_name, MTX_DEF | MTX_DUPOK); \
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else \
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mtx_init(&(k)->uk_lock, (k)->uk_name, \
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"UMA zone", MTX_DEF | MTX_DUPOK); \
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} while (0)
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#define KEG_LOCK_FINI(k) mtx_destroy(&(k)->uk_lock)
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#define KEG_LOCK(k) mtx_lock(&(k)->uk_lock)
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#define KEG_UNLOCK(k) mtx_unlock(&(k)->uk_lock)
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#define ZONE_LOCK(z) mtx_lock((z)->uz_lock)
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#define ZONE_UNLOCK(z) mtx_unlock((z)->uz_lock)
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/*
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* Find a slab within a hash table. This is used for OFFPAGE zones to lookup
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* the slab structure.
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*
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* Arguments:
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* hash The hash table to search.
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* data The base page of the item.
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*
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* Returns:
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* A pointer to a slab if successful, else NULL.
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*/
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static __inline uma_slab_t
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hash_sfind(struct uma_hash *hash, u_int8_t *data)
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{
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uma_slab_t slab;
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int hval;
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hval = UMA_HASH(hash, data);
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SLIST_FOREACH(slab, &hash->uh_slab_hash[hval], us_hlink) {
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if ((u_int8_t *)slab->us_data == data)
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return (slab);
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}
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return (NULL);
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}
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static __inline uma_slab_t
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vtoslab(vm_offset_t va)
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{
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vm_page_t p;
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uma_slab_t slab;
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p = PHYS_TO_VM_PAGE(pmap_kextract(va));
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slab = (uma_slab_t )p->object;
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if (p->flags & PG_SLAB)
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return (slab);
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else
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return (NULL);
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}
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static __inline void
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vsetslab(vm_offset_t va, uma_slab_t slab)
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{
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vm_page_t p;
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p = PHYS_TO_VM_PAGE(pmap_kextract(va));
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p->object = (vm_object_t)slab;
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p->flags |= PG_SLAB;
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}
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static __inline void
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vsetobj(vm_offset_t va, vm_object_t obj)
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{
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vm_page_t p;
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p = PHYS_TO_VM_PAGE(pmap_kextract(va));
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p->object = obj;
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p->flags &= ~PG_SLAB;
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}
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/*
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* The following two functions may be defined by architecture specific code
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* if they can provide more effecient allocation functions. This is useful
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* for using direct mapped addresses.
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*/
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void *uma_small_alloc(uma_zone_t zone, int bytes, u_int8_t *pflag, int wait);
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void uma_small_free(void *mem, int size, u_int8_t flags);
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#endif /* _KERNEL */
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#endif /* VM_UMA_INT_H */
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