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sched/numa: Slow scan rate if no NUMA hinting faults are being recorded 

NUMA PTE scanning slows if a NUMA hinting fault was trapped and no page
was migrated. For long-lived but idle processes there may be no faults
but the scan rate will be high and just waste CPU. This patch will slow
the scan rate for processes that are not trapping faults.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Rik van Riel <riel@redhat.com>
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/1381141781-10992-19-git-send-email-mgorman@suse.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Mel Gorman 2013-10-07 11:28:56 +01:00 committed by Ingo Molnar
parent 598f0ec0bc
commit f307cd1a32
1 changed files with 12 additions and 0 deletions
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12
kernel/sched/fair.c
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@ -1038,6 +1038,18 @@ void task_numa_work(struct callback_head *work)
}
out:
/*
* If the whole process was scanned without updates then no NUMA
* hinting faults are being recorded and scan rate should be lower.
*/
if (mm->numa_scan_offset == 0 && !nr_pte_updates) {
p->numa_scan_period = min(p->numa_scan_period_max,
p->numa_scan_period << 1);
next_scan = now + msecs_to_jiffies(p->numa_scan_period);
mm->numa_next_scan = next_scan;
}
/*
* It is possible to reach the end of the VMA list but the last few
* VMAs are not guaranteed to the vma_migratable. If they are not, we