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| author | Rik van Riel <riel@redhat.com> | 2014-06-23 17:41:35 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2014-07-05 11:17:40 +0200 |
| commit | a22b4b012340b988dbe7a58461d6fcc582f34aa0 (patch) | |
| tree | 0a5a3427d51af5063ed0b8c174f24fa22d064e25 /kernel/sched/fair.c | |
| parent | sched/numa: Rework best node setting in task_numa_migrate() (diff) | |
| download | linux-a22b4b012340b988dbe7a58461d6fcc582f34aa0.tar.xz linux-a22b4b012340b988dbe7a58461d6fcc582f34aa0.zip | |
sched/numa: Change scan period code to match intent
Reading through the scan period code and comment, it appears the
intent was to slow down NUMA scanning when a majority of accesses
are on the local node, specifically a local:remote ratio of 3:1.
However, the code actually tests local / (local + remote), and
the actual cut-off point was around 30% local accesses, well before
a task has actually converged on a node.
Changing the threshold to 7 means scanning slows down when a task
has around 70% of its accesses local, which appears to match the
intent of the code more closely.
Signed-off-by: Rik van Riel <riel@redhat.com>
Cc: mgorman@suse.de
Cc: chegu_vinod@hp.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1403538095-31256-8-git-send-email-riel@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel/sched/fair.c')
| -rw-r--r-- | kernel/sched/fair.c | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 7bb2f464b456..a140c6a8c947 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -1452,12 +1452,12 @@ static void update_numa_active_node_mask(struct numa_group *numa_group) /* * When adapting the scan rate, the period is divided into NUMA_PERIOD_SLOTS * increments. The more local the fault statistics are, the higher the scan - * period will be for the next scan window. If local/remote ratio is below - * NUMA_PERIOD_THRESHOLD (where range of ratio is 1..NUMA_PERIOD_SLOTS) the - * scan period will decrease + * period will be for the next scan window. If local/(local+remote) ratio is + * below NUMA_PERIOD_THRESHOLD (where range of ratio is 1..NUMA_PERIOD_SLOTS) + * the scan period will decrease. Aim for 70% local accesses. */ #define NUMA_PERIOD_SLOTS 10 -#define NUMA_PERIOD_THRESHOLD 3 +#define NUMA_PERIOD_THRESHOLD 7 /* * Increase the scan period (slow down scanning) if the majority of |