Commit f307cd1a authored Oct 07, 2013 by Mel Gorman Committed by Ingo Molnar Oct 09, 2013

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>

parent 598f0ec0

kernel/sched/fair.c

+12 −0

Original line number	Diff line number	Diff line
		@@ -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