| Date | Wed, 20 Mar 2013 21:20:14 -0400 | From | Rik van Riel <> | Subject | Re: [PATCH 05/10] mm: vmscan: Do not allow kswapd to scan at maximum priority |
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On 03/17/2013 09:04 AM, Mel Gorman wrote: > Page reclaim at priority 0 will scan the entire LRU as priority 0 is > considered to be a near OOM condition. Kswapd can reach priority 0 quite > easily if it is encountering a large number of pages it cannot reclaim > such as pages under writeback. When this happens, kswapd reclaims very > aggressively even though there may be no real risk of allocation failure > or OOM. > > This patch prevents kswapd reaching priority 0 and trying to reclaim > the world. Direct reclaimers will still reach priority 0 in the event > of an OOM situation. > > Signed-off-by: Mel Gorman <mgorman@suse.de> > --- > mm/vmscan.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 7513bd1..af3bb6f 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -2891,7 +2891,7 @@ static unsigned long balance_pgdat(pg_data_t *pgdat, int order, > */ > if (raise_priority || !this_reclaimed) > sc.priority--; > - } while (sc.priority >= 0 && > + } while (sc.priority >= 1 && > !pgdat_balanced(pgdat, order, *classzone_idx)); > > out: >
If priority 0 is way way way way way too aggressive, what makes priority 1 safe?
This makes me wonder, are the priorities useful at all to kswapd?
-- All rights reversed
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