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linux-next/include/linux/slub_def.h
Pekka Enberg 5595cffc82 SLUB: dynamic per-cache MIN_PARTIAL
This patch changes the static MIN_PARTIAL to a dynamic per-cache ->min_partial
value that is calculated from object size. The bigger the object size, the more
pages we keep on the partial list.

I tested SLAB, SLUB, and SLUB with this patch on Jens Axboe's 'netio' example
script of the fio benchmarking tool. The script stresses the networking
subsystem which should also give a fairly good beating of kmalloc() et al.

To run the test yourself, first clone the fio repository:

  git clone git://git.kernel.dk/fio.git

and then run the following command n times on your machine:

  time ./fio examples/netio

The results on my 2-way 64-bit x86 machine are as follows:

  [ the minimum, maximum, and average are captured from 50 individual runs ]

                 real time (seconds)
                 min      max      avg      sd
  SLAB           22.76    23.38    22.98    0.17
  SLUB           22.80    25.78    23.46    0.72
  SLUB (dynamic) 22.74    23.54    23.00    0.20

                 sys time (seconds)
                 min      max      avg      sd
  SLAB           6.90     8.28     7.70     0.28
  SLUB           7.42     16.95    8.89     2.28
  SLUB (dynamic) 7.17     8.64     7.73     0.29

                 user time (seconds)
                 min      max      avg      sd
  SLAB           36.89    38.11    37.50    0.29
  SLUB           30.85    37.99    37.06    1.67
  SLUB (dynamic) 36.75    38.07    37.59    0.32

As you can see from the above numbers, this patch brings SLUB to the same level
as SLAB for this particular workload fixing a ~2% regression. I'd expect this
change to help similar workloads that allocate a lot of objects that are close
to the size of a page.

Cc: Matthew Wilcox <matthew@wil.cx>
Cc: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
2008-08-05 09:28:47 +03:00

250 lines
6.7 KiB
C

#ifndef _LINUX_SLUB_DEF_H
#define _LINUX_SLUB_DEF_H
/*
* SLUB : A Slab allocator without object queues.
*
* (C) 2007 SGI, Christoph Lameter
*/
#include <linux/types.h>
#include <linux/gfp.h>
#include <linux/workqueue.h>
#include <linux/kobject.h>
enum stat_item {
ALLOC_FASTPATH, /* Allocation from cpu slab */
ALLOC_SLOWPATH, /* Allocation by getting a new cpu slab */
FREE_FASTPATH, /* Free to cpu slub */
FREE_SLOWPATH, /* Freeing not to cpu slab */
FREE_FROZEN, /* Freeing to frozen slab */
FREE_ADD_PARTIAL, /* Freeing moves slab to partial list */
FREE_REMOVE_PARTIAL, /* Freeing removes last object */
ALLOC_FROM_PARTIAL, /* Cpu slab acquired from partial list */
ALLOC_SLAB, /* Cpu slab acquired from page allocator */
ALLOC_REFILL, /* Refill cpu slab from slab freelist */
FREE_SLAB, /* Slab freed to the page allocator */
CPUSLAB_FLUSH, /* Abandoning of the cpu slab */
DEACTIVATE_FULL, /* Cpu slab was full when deactivated */
DEACTIVATE_EMPTY, /* Cpu slab was empty when deactivated */
DEACTIVATE_TO_HEAD, /* Cpu slab was moved to the head of partials */
DEACTIVATE_TO_TAIL, /* Cpu slab was moved to the tail of partials */
DEACTIVATE_REMOTE_FREES,/* Slab contained remotely freed objects */
ORDER_FALLBACK, /* Number of times fallback was necessary */
NR_SLUB_STAT_ITEMS };
struct kmem_cache_cpu {
void **freelist; /* Pointer to first free per cpu object */
struct page *page; /* The slab from which we are allocating */
int node; /* The node of the page (or -1 for debug) */
unsigned int offset; /* Freepointer offset (in word units) */
unsigned int objsize; /* Size of an object (from kmem_cache) */
#ifdef CONFIG_SLUB_STATS
unsigned stat[NR_SLUB_STAT_ITEMS];
#endif
};
struct kmem_cache_node {
spinlock_t list_lock; /* Protect partial list and nr_partial */
unsigned long nr_partial;
unsigned long min_partial;
struct list_head partial;
#ifdef CONFIG_SLUB_DEBUG
atomic_long_t nr_slabs;
atomic_long_t total_objects;
struct list_head full;
#endif
};
/*
* Word size structure that can be atomically updated or read and that
* contains both the order and the number of objects that a slab of the
* given order would contain.
*/
struct kmem_cache_order_objects {
unsigned long x;
};
/*
* Slab cache management.
*/
struct kmem_cache {
/* Used for retriving partial slabs etc */
unsigned long flags;
int size; /* The size of an object including meta data */
int objsize; /* The size of an object without meta data */
int offset; /* Free pointer offset. */
struct kmem_cache_order_objects oo;
/*
* Avoid an extra cache line for UP, SMP and for the node local to
* struct kmem_cache.
*/
struct kmem_cache_node local_node;
/* Allocation and freeing of slabs */
struct kmem_cache_order_objects max;
struct kmem_cache_order_objects min;
gfp_t allocflags; /* gfp flags to use on each alloc */
int refcount; /* Refcount for slab cache destroy */
void (*ctor)(void *);
int inuse; /* Offset to metadata */
int align; /* Alignment */
const char *name; /* Name (only for display!) */
struct list_head list; /* List of slab caches */
#ifdef CONFIG_SLUB_DEBUG
struct kobject kobj; /* For sysfs */
#endif
#ifdef CONFIG_NUMA
/*
* Defragmentation by allocating from a remote node.
*/
int remote_node_defrag_ratio;
struct kmem_cache_node *node[MAX_NUMNODES];
#endif
#ifdef CONFIG_SMP
struct kmem_cache_cpu *cpu_slab[NR_CPUS];
#else
struct kmem_cache_cpu cpu_slab;
#endif
};
/*
* Kmalloc subsystem.
*/
#if defined(ARCH_KMALLOC_MINALIGN) && ARCH_KMALLOC_MINALIGN > 8
#define KMALLOC_MIN_SIZE ARCH_KMALLOC_MINALIGN
#else
#define KMALLOC_MIN_SIZE 8
#endif
#define KMALLOC_SHIFT_LOW ilog2(KMALLOC_MIN_SIZE)
/*
* We keep the general caches in an array of slab caches that are used for
* 2^x bytes of allocations.
*/
extern struct kmem_cache kmalloc_caches[PAGE_SHIFT + 1];
/*
* Sorry that the following has to be that ugly but some versions of GCC
* have trouble with constant propagation and loops.
*/
static __always_inline int kmalloc_index(size_t size)
{
if (!size)
return 0;
if (size <= KMALLOC_MIN_SIZE)
return KMALLOC_SHIFT_LOW;
#if KMALLOC_MIN_SIZE <= 64
if (size > 64 && size <= 96)
return 1;
if (size > 128 && size <= 192)
return 2;
#endif
if (size <= 8) return 3;
if (size <= 16) return 4;
if (size <= 32) return 5;
if (size <= 64) return 6;
if (size <= 128) return 7;
if (size <= 256) return 8;
if (size <= 512) return 9;
if (size <= 1024) return 10;
if (size <= 2 * 1024) return 11;
if (size <= 4 * 1024) return 12;
/*
* The following is only needed to support architectures with a larger page
* size than 4k.
*/
if (size <= 8 * 1024) return 13;
if (size <= 16 * 1024) return 14;
if (size <= 32 * 1024) return 15;
if (size <= 64 * 1024) return 16;
if (size <= 128 * 1024) return 17;
if (size <= 256 * 1024) return 18;
if (size <= 512 * 1024) return 19;
if (size <= 1024 * 1024) return 20;
if (size <= 2 * 1024 * 1024) return 21;
return -1;
/*
* What we really wanted to do and cannot do because of compiler issues is:
* int i;
* for (i = KMALLOC_SHIFT_LOW; i <= KMALLOC_SHIFT_HIGH; i++)
* if (size <= (1 << i))
* return i;
*/
}
/*
* Find the slab cache for a given combination of allocation flags and size.
*
* This ought to end up with a global pointer to the right cache
* in kmalloc_caches.
*/
static __always_inline struct kmem_cache *kmalloc_slab(size_t size)
{
int index = kmalloc_index(size);
if (index == 0)
return NULL;
return &kmalloc_caches[index];
}
#ifdef CONFIG_ZONE_DMA
#define SLUB_DMA __GFP_DMA
#else
/* Disable DMA functionality */
#define SLUB_DMA (__force gfp_t)0
#endif
void *kmem_cache_alloc(struct kmem_cache *, gfp_t);
void *__kmalloc(size_t size, gfp_t flags);
static __always_inline void *kmalloc_large(size_t size, gfp_t flags)
{
return (void *)__get_free_pages(flags | __GFP_COMP, get_order(size));
}
static __always_inline void *kmalloc(size_t size, gfp_t flags)
{
if (__builtin_constant_p(size)) {
if (size > PAGE_SIZE)
return kmalloc_large(size, flags);
if (!(flags & SLUB_DMA)) {
struct kmem_cache *s = kmalloc_slab(size);
if (!s)
return ZERO_SIZE_PTR;
return kmem_cache_alloc(s, flags);
}
}
return __kmalloc(size, flags);
}
#ifdef CONFIG_NUMA
void *__kmalloc_node(size_t size, gfp_t flags, int node);
void *kmem_cache_alloc_node(struct kmem_cache *, gfp_t flags, int node);
static __always_inline void *kmalloc_node(size_t size, gfp_t flags, int node)
{
if (__builtin_constant_p(size) &&
size <= PAGE_SIZE && !(flags & SLUB_DMA)) {
struct kmem_cache *s = kmalloc_slab(size);
if (!s)
return ZERO_SIZE_PTR;
return kmem_cache_alloc_node(s, flags, node);
}
return __kmalloc_node(size, flags, node);
}
#endif
#endif /* _LINUX_SLUB_DEF_H */