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| author | Jack Steiner <steiner@sgi.com> | 2010-05-26 14:42:49 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2010-05-27 09:12:44 -0700 |
| commit | 6adef3ebe570bcde67fd6c16101451ddde5712b5 (patch) | |
| tree | 0f60e2a4d01850ae33aee6cefc7a59845ede89a0 /include/linux/sched.h | |
| parent | 2c488db27b614816024e7994117f599337de0f34 (diff) | |
| download | linux-3.10-6adef3ebe570bcde67fd6c16101451ddde5712b5.tar.gz linux-3.10-6adef3ebe570bcde67fd6c16101451ddde5712b5.tar.bz2 linux-3.10-6adef3ebe570bcde67fd6c16101451ddde5712b5.zip | |
cpusets: new round-robin rotor for SLAB allocations
We have observed several workloads running on multi-node systems where
memory is assigned unevenly across the nodes in the system. There are
numerous reasons for this but one is the round-robin rotor in
cpuset_mem_spread_node().
For example, a simple test that writes a multi-page file will allocate
pages on nodes 0 2 4 6 ... Odd nodes are skipped. (Sometimes it
allocates on odd nodes & skips even nodes).
An example is shown below. The program "lfile" writes a file consisting
of 10 pages. The program then mmaps the file & uses get_mempolicy(...,
MPOL_F_NODE) to determine the nodes where the file pages were allocated.
The output is shown below:
# ./lfile
allocated on nodes: 2 4 6 0 1 2 6 0 2
There is a single rotor that is used for allocating both file pages & slab
pages. Writing the file allocates both a data page & a slab page
(buffer_head). This advances the RR rotor 2 nodes for each page
allocated.
A quick confirmation seems to confirm this is the cause of the uneven
allocation:
# echo 0 >/dev/cpuset/memory_spread_slab
# ./lfile
allocated on nodes: 6 7 8 9 0 1 2 3 4 5
This patch introduces a second rotor that is used for slab allocations.
Signed-off-by: Jack Steiner <steiner@sgi.com>
Acked-by: 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 'include/linux/sched.h')
| -rw-r--r-- | include/linux/sched.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/sched.h b/include/linux/sched.h index c0151ffd354..4f31a166b1a 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1423,6 +1423,7 @@ struct task_struct { nodemask_t mems_allowed; /* Protected by alloc_lock */ int mems_allowed_change_disable; int cpuset_mem_spread_rotor; + int cpuset_slab_spread_rotor; #endif #ifdef CONFIG_CGROUPS /* Control Group info protected by css_set_lock */ |