Messages in this thread | | | Date | Fri, 22 Mar 2013 08:08:56 +0800 | From | Will Huck <> | Subject | Re: [PATCH 01/10] mm: vmscan: Limit the number of pages kswapd reclaims at each priority |
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Hi Rik, On 03/21/2013 08:52 AM, Rik van Riel wrote: > On 03/20/2013 12:18 PM, Michal Hocko wrote: >> On Sun 17-03-13 13:04:07, Mel Gorman wrote: >> [...] >>> diff --git a/mm/vmscan.c b/mm/vmscan.c >>> index 88c5fed..4835a7a 100644 >>> --- a/mm/vmscan.c >>> +++ b/mm/vmscan.c >>> @@ -2593,6 +2593,32 @@ static bool prepare_kswapd_sleep(pg_data_t >>> *pgdat, int order, long remaining, >>> } >>> >>> /* >>> + * kswapd shrinks the zone by the number of pages required to reach >>> + * the high watermark. >>> + */ >>> +static void kswapd_shrink_zone(struct zone *zone, >>> + struct scan_control *sc, >>> + unsigned long lru_pages) >>> +{ >>> + unsigned long nr_slab; >>> + struct reclaim_state *reclaim_state = current->reclaim_state; >>> + struct shrink_control shrink = { >>> + .gfp_mask = sc->gfp_mask, >>> + }; >>> + >>> + /* Reclaim above the high watermark. */ >>> + sc->nr_to_reclaim = max(SWAP_CLUSTER_MAX, high_wmark_pages(zone)); >> >> OK, so the cap is at high watermark which sounds OK to me, although I >> would expect balance_gap being considered here. Is it not used >> intentionally or you just wanted to have a reasonable upper bound? >> >> I am not objecting to that it just hit my eyes. > > This is the maximum number of pages to reclaim, not the point > at which to stop reclaiming.
What's the difference between the maximum number of pages to reclaim and the point at which to stop reclaiming?
> > I assume Mel chose this value because it guarantees that enough > pages will have been freed, while also making sure that the value > is scaled according to zone size (keeping pressure between zones > roughly equal). >
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