ChangeSet 1.2231.1.7, 2005/03/28 19:18:09-08:00, [EMAIL PROTECTED]
[PATCH] slab.[ch]: kmalloc() cleanups
I found a new idea for optimizing the loop in kmalloc - now the cleanup
both reduces the size of the .text segment in mm/slab.o and speeds up
largs
kmallocs a bit. I still loose 2 cycles for kmalloc(32,GFP_KERNEL)
compared
to the current code, but I haven't figured out how I could optimize
further.
- inline kmem_find_general_cachep()
- optimize kmem_find_general_cachep() and document the optimization.
- remove duplicate code from __kmalloc(): call
kmem_find_general_cachep()
directly.
Based on a patch from Renaud Lienhart <[EMAIL PROTECTED]>
Signed-off-by: Manfred Spraul <[EMAIL PROTECTED]>
Signed-off-by: Andrew Morton <[EMAIL PROTECTED]>
Signed-off-by: Linus Torvalds <[EMAIL PROTECTED]>
slab.c | 52 +++++++++++++++++++++++++---------------------------
1 files changed, 25 insertions(+), 27 deletions(-)
diff -Nru a/mm/slab.c b/mm/slab.c
--- a/mm/slab.c 2005-03-28 21:07:46 -08:00
+++ b/mm/slab.c 2005-03-28 21:07:46 -08:00
@@ -507,7 +507,7 @@
struct cache_sizes malloc_sizes[] = {
#define CACHE(x) { .cs_size = (x) },
#include <linux/kmalloc_sizes.h>
- { 0, }
+ CACHE(ULONG_MAX)
#undef CACHE
};
@@ -584,20 +584,28 @@
return cachep->array[smp_processor_id()];
}
-static kmem_cache_t * kmem_find_general_cachep (size_t size, int gfpflags)
+static inline kmem_cache_t *kmem_find_general_cachep (size_t size, int
gfpflags)
{
struct cache_sizes *csizep = malloc_sizes;
- /* This function could be moved to the header file, and
- * made inline so consumers can quickly determine what
- * cache pointer they require.
+#if DEBUG
+ /* This happens if someone tries to call
+ * kmem_cache_create(), or __kmalloc(), before
+ * the generic caches are initialized.
+ */
+ BUG_ON(csizep->cs_cachep == NULL);
+#endif
+ while (size > csizep->cs_size)
+ csizep++;
+
+ /*
+ * Really subtile: The last entry with cs->cs_size==ULONG_MAX
+ * has cs_{dma,}cachep==NULL. Thus no special case
+ * for large kmalloc calls required.
*/
- for ( ; csizep->cs_size; csizep++) {
- if (size > csizep->cs_size)
- continue;
- break;
- }
- return (gfpflags & GFP_DMA) ? csizep->cs_dmacachep : csizep->cs_cachep;
+ if (unlikely(gfpflags & GFP_DMA))
+ return csizep->cs_dmacachep;
+ return csizep->cs_cachep;
}
/* Cal the num objs, wastage, and bytes left over for a given slab size. */
@@ -796,7 +804,7 @@
sizes = malloc_sizes;
names = cache_names;
- while (sizes->cs_size) {
+ while (sizes->cs_size != ULONG_MAX) {
/* For performance, all the general caches are L1 aligned.
* This should be particularly beneficial on SMP boxes, as it
* eliminates "false sharing".
@@ -2455,22 +2463,12 @@
*/
void * __kmalloc (size_t size, int flags)
{
- struct cache_sizes *csizep = malloc_sizes;
+ kmem_cache_t *cachep;
- for (; csizep->cs_size; csizep++) {
- if (size > csizep->cs_size)
- continue;
-#if DEBUG
- /* This happens if someone tries to call
- * kmem_cache_create(), or kmalloc(), before
- * the generic caches are initialized.
- */
- BUG_ON(csizep->cs_cachep == NULL);
-#endif
- return __cache_alloc(flags & GFP_DMA ?
- csizep->cs_dmacachep : csizep->cs_cachep, flags);
- }
- return NULL;
+ cachep = kmem_find_general_cachep(size, flags);
+ if (unlikely(cachep == NULL))
+ return NULL;
+ return __cache_alloc(cachep, flags);
}
EXPORT_SYMBOL(__kmalloc);
-
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