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author | Shaohua Li <shaohua.li@intel.com> | 2011-08-26 02:59:12 +0400 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2011-08-26 03:25:34 +0400 |
commit | 439423f6894aa0dec22187526827456f5004baed (patch) | |
tree | 1f22238a24b83e0beb1467a1f73b0db952c69894 /drivers/net/rionet.c | |
parent | 4c30c6f566c0989ddaee3407da44751e340a63ed (diff) | |
download | linux-439423f6894aa0dec22187526827456f5004baed.tar.xz |
vmscan: clear ZONE_CONGESTED for zone with good watermark
ZONE_CONGESTED is only cleared in kswapd, but pages can be freed in any
task. It's possible ZONE_CONGESTED isn't cleared in some cases:
1. the zone is already balanced just entering balance_pgdat() for
order-0 because concurrent tasks free memory. In this case, later
check will skip the zone as it's balanced so the flag isn't cleared.
2. high order balance fallbacks to order-0. quote from Mel: At the
end of balance_pgdat(), kswapd uses the following logic;
If reclaiming at high order {
for each zone {
if all_unreclaimable
skip
if watermark is not met
order = 0
loop again
/* watermark is met */
clear congested
}
}
i.e. it clears ZONE_CONGESTED if it the zone is balanced. if not,
it restarts balancing at order-0. However, if the higher zones are
balanced for order-0, kswapd will miss clearing ZONE_CONGESTED as
that only happens after a zone is shrunk. This can mean that
wait_iff_congested() stalls unnecessarily.
This patch makes kswapd clear ZONE_CONGESTED during its initial
highmem->dma scan for zones that are already balanced.
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/net/rionet.c')
0 files changed, 0 insertions, 0 deletions