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[PATCH] slab: Remove SLAB_NO_REAP option 

SLAB_NO_REAP is documented as an option that will cause this slab not to be
reaped under memory pressure.  However, that is not what happens.  The only
thing that SLAB_NO_REAP controls at the moment is the reclaim of the unused
slab elements that were allocated in batch in cache_reap().  Cache_reap()
is run every few seconds independently of memory pressure.

Could we remove the whole thing?  Its only used by three slabs anyways and
I cannot find a reason for having this option.

There is an additional problem with SLAB_NO_REAP.  If set then the recovery
of objects from alien caches is switched off.  Objects not freed on the
same node where they were initially allocated will only be reused if a
certain amount of objects accumulates from one alien node (not very likely)
or if the cache is explicitly shrunk.  (Strangely __cache_shrink does not
check for SLAB_NO_REAP)

Getting rid of SLAB_NO_REAP fixes the problems with alien cache freeing.

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Manfred Spraul <manfred@colorfullife.com>
Cc: Mark Fasheh <mark.fasheh@oracle.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Christoph Lameter 2006-03-22 00:08:15 -08:00 committed by Linus Torvalds
parent 911851e6ee
commit ac2b898ca6
4 changed files with 4 additions and 14 deletions
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2
drivers/scsi/iscsi_tcp.c
View File

@ -3639,7 +3639,7 @@ iscsi_tcp_init(void)
taskcache = kmem_cache_create("iscsi_taskcache",
sizeof(struct iscsi_data_task), 0,
SLAB_HWCACHE_ALIGN | SLAB_NO_REAP, NULL, NULL);
SLAB_HWCACHE_ALIGN, NULL, NULL);
if (!taskcache)
return -ENOMEM;

2
fs/ocfs2/super.c
View File

@ -959,7 +959,7 @@ static int ocfs2_initialize_mem_caches(void)
ocfs2_lock_cache = kmem_cache_create("ocfs2_lock",
sizeof(struct ocfs2_journal_lock),
0,
SLAB_NO_REAP|SLAB_HWCACHE_ALIGN,
SLAB_HWCACHE_ALIGN,
NULL, NULL);
if (!ocfs2_lock_cache)
return -ENOMEM;

1
include/linux/slab.h
View File

@ -38,7 +38,6 @@ typedef struct kmem_cache kmem_cache_t;
#define SLAB_DEBUG_INITIAL 0x00000200UL /* Call constructor (as verifier) */
#define SLAB_RED_ZONE 0x00000400UL /* Red zone objs in a cache */
#define SLAB_POISON 0x00000800UL /* Poison objects */
#define SLAB_NO_REAP 0x00001000UL /* never reap from the cache */
#define SLAB_HWCACHE_ALIGN 0x00002000UL /* align objs on a h/w cache lines */
#define SLAB_CACHE_DMA 0x00004000UL /* use GFP_DMA memory */
#define SLAB_MUST_HWCACHE_ALIGN 0x00008000UL /* force alignment */

13
mm/slab.c
View File

@ -170,12 +170,12 @@
#if DEBUG
# define CREATE_MASK (SLAB_DEBUG_INITIAL | SLAB_RED_ZONE | \
SLAB_POISON | SLAB_HWCACHE_ALIGN | \
SLAB_NO_REAP | SLAB_CACHE_DMA | \
SLAB_CACHE_DMA | \
SLAB_MUST_HWCACHE_ALIGN | SLAB_STORE_USER | \
SLAB_RECLAIM_ACCOUNT | SLAB_PANIC | \
SLAB_DESTROY_BY_RCU)
#else
# define CREATE_MASK (SLAB_HWCACHE_ALIGN | SLAB_NO_REAP | \
# define CREATE_MASK (SLAB_HWCACHE_ALIGN | \
SLAB_CACHE_DMA | SLAB_MUST_HWCACHE_ALIGN | \
SLAB_RECLAIM_ACCOUNT | SLAB_PANIC | \
SLAB_DESTROY_BY_RCU)
@ -662,7 +662,6 @@ static struct kmem_cache cache_cache = {
.limit = BOOT_CPUCACHE_ENTRIES,
.shared = 1,
.buffer_size = sizeof(struct kmem_cache),
.flags = SLAB_NO_REAP,
.name = "kmem_cache",
#if DEBUG
.obj_size = sizeof(struct kmem_cache),
@ -1848,9 +1847,6 @@ static void setup_cpu_cache(struct kmem_cache *cachep)
* %SLAB_RED_ZONE - Insert `Red' zones around the allocated memory to check
* for buffer overruns.
*
* %SLAB_NO_REAP - Don't automatically reap this cache when we're under
* memory pressure.
*
* %SLAB_HWCACHE_ALIGN - Align the objects in this cache to a hardware
* cacheline. This can be beneficial if you're counting cycles as closely
* as davem.
@ -3584,10 +3580,6 @@ static void cache_reap(void *unused)
struct slab *slabp;
searchp = list_entry(walk, struct kmem_cache, next);
if (searchp->flags & SLAB_NO_REAP)
goto next;
check_irq_on();
l3 = searchp->nodelists[numa_node_id()];
@ -3635,7 +3627,6 @@ static void cache_reap(void *unused)
} while (--tofree > 0);
next_unlock:
spin_unlock_irq(&l3->list_lock);
next:
cond_resched();
}
check_irq_on();