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authorChristoph Lameter <clameter@sgi.com>2008-04-14 12:11:41 -0400
committerPekka Enberg <penberg@cs.helsinki.fi>2008-04-27 11:28:40 -0400
commit9b2cd506e5f2117f94c28a0040bf5da058105316 (patch)
tree670857a0cea6723124301901cb5261811c64d701 /mm
parent114e9e89e668ec561c9b0f3dea7bcc8af7c29d21 (diff)
slub: Calculate min_objects based on number of processors.
The mininum objects per slab is calculated based on the number of processors that may come online. Processors min_objects --------------------------- 1 8 2 12 4 16 8 20 16 24 32 28 64 32 1024 48 4096 56 The higher the number of processors the large the order sizes used for various slab caches will become. This has been shown to address the performance issues in hackbench on 16p etc. The calculation is only performed if slub_min_objects is zero (default). If one specifies a slub_min_objects on boot then that setting is taken. As suggested by Zhang Yanmin's performance tests on 16-core Tigerton, use the formula '4 * (fls(nr_cpu_ids) + 1)': ./hackbench 100 process 2000: 1) 2.6.25-rc6slab: 23.5 seconds 2) 2.6.25-rc7SLUB+slub_min_objects=20: 31 seconds 3) 2.6.25-rc7SLUB+slub_min_objects=24: 23.5 seconds Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Zhang Yanmin <yanmin.zhang@intel.com> Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
Diffstat (limited to 'mm')
-rw-r--r--mm/slub.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/mm/slub.c b/mm/slub.c
index 6572cef0c43c..e2e6ba7a5172 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1803,7 +1803,7 @@ static struct page *get_object_page(const void *x)
1803 */ 1803 */
1804static int slub_min_order; 1804static int slub_min_order;
1805static int slub_max_order = PAGE_ALLOC_COSTLY_ORDER; 1805static int slub_max_order = PAGE_ALLOC_COSTLY_ORDER;
1806static int slub_min_objects = 4; 1806static int slub_min_objects;
1807 1807
1808/* 1808/*
1809 * Merge control. If this is set then no merging of slab caches will occur. 1809 * Merge control. If this is set then no merging of slab caches will occur.
@@ -1880,6 +1880,8 @@ static inline int calculate_order(int size)
1880 * we reduce the minimum objects required in a slab. 1880 * we reduce the minimum objects required in a slab.
1881 */ 1881 */
1882 min_objects = slub_min_objects; 1882 min_objects = slub_min_objects;
1883 if (!min_objects)
1884 min_objects = 4 * (fls(nr_cpu_ids) + 1);
1883 while (min_objects > 1) { 1885 while (min_objects > 1) {
1884 fraction = 8; 1886 fraction = 8;
1885 while (fraction >= 4) { 1887 while (fraction >= 4) {