path: root/mm/slab.c
diff options
authorEric Dumazet <dada1@cosmosbay.com>2007-05-06 14:49:27 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-05-07 12:12:52 -0700
commit364fbb29a0105863d76a1f7bbc01783a4af30a75 (patch)
tree065828ff023a95daa3b60abbb166e71f10336a64 /mm/slab.c
parent6ce745ed39d35f9d547d00d406db2be7c6c175b3 (diff)
SLAB: use num_possible_cpus() in enable_cpucache()
The existing comment in mm/slab.c is *perfect*, so I reproduce it : /* * CPU bound tasks (e.g. network routing) can exhibit cpu bound * allocation behaviour: Most allocs on one cpu, most free operations * on another cpu. For these cases, an efficient object passing between * cpus is necessary. This is provided by a shared array. The array * replaces Bonwick's magazine layer. * On uniprocessor, it's functionally equivalent (but less efficient) * to a larger limit. Thus disabled by default. */ As most shiped linux kernels are now compiled with CONFIG_SMP, there is no way a preprocessor #if can detect if the machine is UP or SMP. Better to use num_possible_cpus(). This means on UP we allocate a 'size=0 shared array', to be more efficient. Another patch can later avoid the allocations of 'empty shared arrays', to save some memory. Signed-off-by: Eric Dumazet <dada1@cosmosbay.com> Acked-by: Pekka Enberg <penberg@cs.helsinki.fi> Acked-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/slab.c')
1 files changed, 1 insertions, 3 deletions
diff --git a/mm/slab.c b/mm/slab.c
index 21b2aef2525..ae440b5ba60 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -4033,10 +4033,8 @@ static int enable_cpucache(struct kmem_cache *cachep)
* to a larger limit. Thus disabled by default.
shared = 0;
-#ifdef CONFIG_SMP
- if (cachep->buffer_size <= PAGE_SIZE)
+ if (cachep->buffer_size <= PAGE_SIZE && num_possible_cpus() > 1)
shared = 8;