diff options
author | Jack Steiner <steiner@sgi.com> | 2010-05-26 21:42:49 (GMT) |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2010-05-27 16:12:44 (GMT) |
commit | 6adef3ebe570bcde67fd6c16101451ddde5712b5 (patch) | |
tree | 0f60e2a4d01850ae33aee6cefc7a59845ede89a0 | |
parent | 2c488db27b614816024e7994117f599337de0f34 (diff) | |
download | linux-6adef3ebe570bcde67fd6c16101451ddde5712b5.tar.xz |
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>
-rw-r--r-- | include/linux/cpuset.h | 6 | ||||
-rw-r--r-- | include/linux/sched.h | 1 | ||||
-rw-r--r-- | kernel/cpuset.c | 20 | ||||
-rw-r--r-- | mm/slab.c | 2 |
4 files changed, 24 insertions, 5 deletions
diff --git a/include/linux/cpuset.h b/include/linux/cpuset.h index 20b51ca..457ed76 100644 --- a/include/linux/cpuset.h +++ b/include/linux/cpuset.h @@ -69,6 +69,7 @@ extern void cpuset_task_status_allowed(struct seq_file *m, struct task_struct *task); extern int cpuset_mem_spread_node(void); +extern int cpuset_slab_spread_node(void); static inline int cpuset_do_page_mem_spread(void) { @@ -194,6 +195,11 @@ static inline int cpuset_mem_spread_node(void) return 0; } +static inline int cpuset_slab_spread_node(void) +{ + return 0; +} + static inline int cpuset_do_page_mem_spread(void) { return 0; diff --git a/include/linux/sched.h b/include/linux/sched.h index c0151ff..4f31a16 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 */ diff --git a/kernel/cpuset.c b/kernel/cpuset.c index 61d6af7..02b9611 100644 --- a/kernel/cpuset.c +++ b/kernel/cpuset.c @@ -2469,7 +2469,8 @@ void cpuset_unlock(void) } /** - * cpuset_mem_spread_node() - On which node to begin search for a page + * cpuset_mem_spread_node() - On which node to begin search for a file page + * cpuset_slab_spread_node() - On which node to begin search for a slab page * * If a task is marked PF_SPREAD_PAGE or PF_SPREAD_SLAB (as for * tasks in a cpuset with is_spread_page or is_spread_slab set), @@ -2494,16 +2495,27 @@ void cpuset_unlock(void) * See kmem_cache_alloc_node(). */ -int cpuset_mem_spread_node(void) +static int cpuset_spread_node(int *rotor) { int node; - node = next_node(current->cpuset_mem_spread_rotor, current->mems_allowed); + node = next_node(*rotor, current->mems_allowed); if (node == MAX_NUMNODES) node = first_node(current->mems_allowed); - current->cpuset_mem_spread_rotor = node; + *rotor = node; return node; } + +int cpuset_mem_spread_node(void) +{ + return cpuset_spread_node(¤t->cpuset_mem_spread_rotor); +} + +int cpuset_slab_spread_node(void) +{ + return cpuset_spread_node(¤t->cpuset_slab_spread_rotor); +} + EXPORT_SYMBOL_GPL(cpuset_mem_spread_node); /** @@ -3219,7 +3219,7 @@ static void *alternate_node_alloc(struct kmem_cache *cachep, gfp_t flags) nid_alloc = nid_here = numa_node_id(); get_mems_allowed(); if (cpuset_do_slab_mem_spread() && (cachep->flags & SLAB_MEM_SPREAD)) - nid_alloc = cpuset_mem_spread_node(); + nid_alloc = cpuset_slab_spread_node(); else if (current->mempolicy) nid_alloc = slab_node(current->mempolicy); put_mems_allowed(); |