diff options
author | Jack Steiner <steiner@sgi.com> | 2010-05-26 14:42:51 -0700 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2010-05-27 09:12:44 -0700 |
commit | 0ac0c0d0f837c499afd02a802f9cf52d3027fa3b (patch) | |
tree | c20a7306d4b727722556af1aa5565855686aee07 /arch | |
parent | 6adef3ebe570bcde67fd6c16101451ddde5712b5 (diff) |
cpusets: randomize node rotor used in cpuset_mem_spread_node()
Some workloads that create a large number of small files tend to assign
too many pages to node 0 (multi-node systems). Part of the reason is that
the rotor (in cpuset_mem_spread_node()) used to assign nodes starts at
node 0 for newly created tasks.
This patch changes the rotor to be initialized to a random node number of
the cpuset.
[akpm@linux-foundation.org: fix layout]
[Lee.Schermerhorn@hp.com: Define stub numa_random() for !NUMA configuration]
Signed-off-by: Jack Steiner <steiner@sgi.com>
Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Paul Menage <menage@google.com>
Cc: Jack Steiner <steiner@sgi.com>
Cc: Robin Holt <holt@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch')
-rw-r--r-- | arch/x86/mm/numa.c | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/arch/x86/mm/numa.c b/arch/x86/mm/numa.c index 550df481acc..10c27bb1e95 100644 --- a/arch/x86/mm/numa.c +++ b/arch/x86/mm/numa.c @@ -2,6 +2,7 @@ #include <linux/topology.h> #include <linux/module.h> #include <linux/bootmem.h> +#include <linux/random.h> #ifdef CONFIG_DEBUG_PER_CPU_MAPS # define DBG(x...) printk(KERN_DEBUG x) @@ -65,3 +66,19 @@ const struct cpumask *cpumask_of_node(int node) } EXPORT_SYMBOL(cpumask_of_node); #endif + +/* + * Return the bit number of a random bit set in the nodemask. + * (returns -1 if nodemask is empty) + */ +int __node_random(const nodemask_t *maskp) +{ + int w, bit = -1; + + w = nodes_weight(*maskp); + if (w) + bit = bitmap_ord_to_pos(maskp->bits, + get_random_int() % w, MAX_NUMNODES); + return bit; +} +EXPORT_SYMBOL(__node_random); |