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 <[email protected]>
Index: linux-2.6.16-rc4/mm/slab.c
===================================================================
--- linux-2.6.16-rc4.orig/mm/slab.c 2006-02-17 14:23:45.000000000 -0800
+++ linux-2.6.16-rc4/mm/slab.c 2006-02-22 14:06:23.000000000 -0800
@@ -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)
@@ -642,7 +642,7 @@ static struct kmem_cache cache_cache = {
.limit = BOOT_CPUCACHE_ENTRIES,
.shared = 1,
.buffer_size = sizeof(struct kmem_cache),
- .flags = SLAB_NO_REAP,
+ .flags = 0,
.spinlock = SPIN_LOCK_UNLOCKED,
.name = "kmem_cache",
#if DEBUG
@@ -1689,9 +1689,6 @@ static inline size_t calculate_slab_orde
* %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.
@@ -3487,10 +3484,6 @@ 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()];
Index: linux-2.6.16-rc4/include/linux/slab.h
===================================================================
--- linux-2.6.16-rc4.orig/include/linux/slab.h 2006-02-17 14:23:45.000000000 -0800
+++ linux-2.6.16-rc4/include/linux/slab.h 2006-02-22 14:05:25.000000000 -0800
@@ -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 */
Index: linux-2.6.16-rc4/drivers/scsi/iscsi_tcp.c
===================================================================
--- linux-2.6.16-rc4.orig/drivers/scsi/iscsi_tcp.c 2006-02-17 14:23:45.000000000 -0800
+++ linux-2.6.16-rc4/drivers/scsi/iscsi_tcp.c 2006-02-22 14:08:46.000000000 -0800
@@ -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;
Index: linux-2.6.16-rc4/fs/ocfs2/super.c
===================================================================
--- linux-2.6.16-rc4.orig/fs/ocfs2/super.c 2006-02-17 14:23:45.000000000 -0800
+++ linux-2.6.16-rc4/fs/ocfs2/super.c 2006-02-22 14:08:17.000000000 -0800
@@ -959,7 +959,7 @@ static int ocfs2_initialize_mem_caches(v
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;
-
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