Messages in this thread | | | Date | Wed, 19 Feb 2020 15:02:15 +0000 | From | Mel Gorman <> | Subject | Re: [PATCH v17 8/9] mm/page_reporting: Add budget limit on how many pages can be reported per pass |
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On Tue, Feb 11, 2020 at 02:47:19PM -0800, Alexander Duyck wrote: > From: Alexander Duyck <alexander.h.duyck@linux.intel.com> > > In order to keep ourselves from reporting pages that are just going to be > reused again in the case of heavy churn we can put a limit on how many > total pages we will process per pass. Doing this will allow the worker > thread to go into idle much more quickly so that we avoid competing with > other threads that might be allocating or freeing pages. > > The logic added here will limit the worker thread to no more than one > sixteenth of the total free pages in a given area per list. Once that limit > is reached it will update the state so that at the end of the pass we will > reschedule the worker to try again in 2 seconds when the memory churn has > hopefully settled down. > > Again this optimization doesn't show much of a benefit in the standard case > as the memory churn is minmal. However with page allocator shuffling > enabled the gain is quite noticeable. Below are the results with a THP > enabled version of the will-it-scale page_fault1 test showing the > improvement in iterations for 16 processes or threads. > > Without: > tasks processes processes_idle threads threads_idle > 16 8283274.75 0.17 5594261.00 38.15 > > With: > tasks processes processes_idle threads threads_idle > 16 8767010.50 0.21 5791312.75 36.98 > > Signed-off-by: Alexander Duyck <alexander.h.duyck@linux.intel.com>
Seems fair. The test case you used would have been pounding on the zone lock at fairly high frequency so it represents a worst-case scenario but not necessarily an unrealistic one
Acked-by: Mel Gorman <mgorman@techsingularity.net>
-- Mel Gorman SUSE Labs
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