On Thu, 2016-04-07 at 20:28 +0300, Ebru Akagunduz wrote: > Currently khugepaged makes swapin readahead to improve > THP collapse rate. This patch checks vm statistics > to avoid workload of swapin, if unnecessary. So that > when system under pressure, khugepaged won't consume > resources to swapin and won't trigger direct reclaim > when swapin readahead. > > The patch was tested with a test program that allocates > 800MB of memory, writes to it, and then sleeps. The system > was forced to swap out all. Afterwards, the test program > touches the area by writing, it skips a page in each > 20 pages of the area. When waiting to swapin readahead > left part of the test, the memory forced to be busy > doing page reclaim. There was enough free memory during > test, khugepaged did not swapin readahead due to business. > > Test results: > > After swapped out > ------------------------------------------------------------------- > | Anonymous | AnonHugePages | Swap | Fraction | > ------------------------------------------------------------------- > With patch | 0 kB | 0 kB | 800000 kB | %100 | > ------------------------------------------------------------------- > Without patch | 0 kB | 0 kB | 800000 kB | %100 | > ------------------------------------------------------------------- > > After swapped in > ------------------------------------------------------------------- > | Anonymous | AnonHugePages | Swap | Fraction | > ------------------------------------------------------------------- > With patch | 384812 kB | 96256 kB | 415188 kB | %25 | > ------------------------------------------------------------------- > Without patch | 389728 kB | 194560 kB | 410272 kB | %49 | > ------------------------------------------------------------------- > > Signed-off-by: Ebru Akagunduz <ebru.akagunduz@xxxxxxxxx> Acked-by: Rik van Riel <riel@xxxxxxxxxx> -- All Rights Reversed.
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