diff options
author | Rik van Riel <riel@redhat.com> | 2013-10-07 11:29:39 +0100 |
---|---|---|
committer | Ingo Molnar <mingo@kernel.org> | 2013-10-09 14:48:21 +0200 |
commit | de1c9ce6f07fec0381a39a9d0b379ea35aa1167f (patch) | |
tree | d96bf1a2b25dfa84d3fe5f6fe00fb780800e3ef3 /kernel/sched | |
parent | 1e3646ffc64b232cb14a5ef01d7b98997c1b73f9 (diff) | |
download | linux-de1c9ce6f07fec0381a39a9d0b379ea35aa1167f.tar.gz |
sched/numa: Skip some page migrations after a shared fault
Shared faults can lead to lots of unnecessary page migrations, slowing down the system, and causing private faults to hit the per-pgdat migration ratelimit. This patch adds sysctl numa_balancing_migrate_deferred, which specifies how many shared page migrations to skip unconditionally, after each page migration that is skipped because it is a shared fault. This reduces the number of page migrations back and forth in shared fault situations. It also gives a strong preference to the tasks that are already running where most of the memory is, and to moving the other tasks to near the memory. Testing this with a much higher scan rate than the default still seems to result in fewer page migrations than before. Memory seems to be somewhat better consolidated than previously, with multi-instance specjbb runs on a 4 node system. Signed-off-by: Rik van Riel <riel@redhat.com> Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1381141781-10992-62-git-send-email-mgorman@suse.de Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/sched')
-rw-r--r-- | kernel/sched/fair.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 8454c38b1b12..e7884dc3416d 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -833,6 +833,14 @@ unsigned int sysctl_numa_balancing_scan_size = 256; /* Scan @scan_size MB every @scan_period after an initial @scan_delay in ms */ unsigned int sysctl_numa_balancing_scan_delay = 1000; +/* + * After skipping a page migration on a shared page, skip N more numa page + * migrations unconditionally. This reduces the number of NUMA migrations + * in shared memory workloads, and has the effect of pulling tasks towards + * where their memory lives, over pulling the memory towards the task. + */ +unsigned int sysctl_numa_balancing_migrate_deferred = 16; + static unsigned int task_nr_scan_windows(struct task_struct *p) { unsigned long rss = 0; |