Messages in this thread | | | Date | Wed, 6 Jul 2016 09:31:21 +0100 | From | Mel Gorman <> | Subject | Re: [PATCH 08/31] mm, vmscan: simplify the logic deciding whether kswapd sleeps |
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On Wed, Jul 06, 2016 at 09:30:54AM +0900, Minchan Kim wrote: > On Tue, Jul 05, 2016 at 11:26:39AM +0100, Mel Gorman wrote: > > <snip> > > > > > @@ -3418,10 +3426,10 @@ void wakeup_kswapd(struct zone *zone, int order, enum zone_type classzone_idx) > > > > if (!cpuset_zone_allowed(zone, GFP_KERNEL | __GFP_HARDWALL)) > > > > return; > > > > pgdat = zone->zone_pgdat; > > > > - if (pgdat->kswapd_max_order < order) { > > > > - pgdat->kswapd_max_order = order; > > > > - pgdat->classzone_idx = min(pgdat->classzone_idx, classzone_idx); > > > > - } > > > > + if (pgdat->kswapd_classzone_idx == -1) > > > > + pgdat->kswapd_classzone_idx = classzone_idx; > > > > > > It's tricky. Couldn't we change kswapd_classzone_idx to integer type > > > and remove if above if condition? > > > > > > > It's tricky and not necessarily better overall. It's perfectly possible > > to be woken up for zone index 0 so it's changing -1 to another magic > > value. > > I don't get it. What is a problem with this? >
It becomes difficult to tell the difference between "no wakeup and init to zone 0" and "wakeup and reclaim for zone 0". At least that's the problem I ran into when I tried before settling on -1.
-- Mel Gorman SUSE Labs
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