Messages in this thread | | | Date | Wed, 13 Jul 2016 09:40:37 +0100 | From | Mel Gorman <> | Subject | Re: [PATCH 11/34] mm, vmscan: remove duplicate logic clearing node congestion and dirty state |
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On Tue, Jul 12, 2016 at 10:22:56AM -0400, Johannes Weiner wrote: > On Fri, Jul 08, 2016 at 10:34:47AM +0100, Mel Gorman wrote: > > @@ -3008,7 +3008,17 @@ static bool zone_balanced(struct zone *zone, int order, int classzone_idx) > > { > > unsigned long mark = high_wmark_pages(zone); > > > > - return zone_watermark_ok_safe(zone, order, mark, classzone_idx); > > + if (!zone_watermark_ok_safe(zone, order, mark, classzone_idx)) > > + return false; > > + > > + /* > > + * If any eligible zone is balanced then the node is not considered > > + * to be congested or dirty > > + */ > > + clear_bit(PGDAT_CONGESTED, &zone->zone_pgdat->flags); > > + clear_bit(PGDAT_DIRTY, &zone->zone_pgdat->flags); > > Predicate functions that secretly modify internal state give me the > willies... The diffstat is flat, too. Is this really an improvement?
Primarily, it's about less duplicated code and maintenance overhead. Overall I was both trying to remove side-effects and make the kswapd flow easier to follow.
I'm open to renaming suggestions that make it clear the function has side-effects. Best I came up with after the first coffee is try_reset_zone_balanced() which returns true with congestion/dirty state cleared if the zone is balanced. The name is not great because it's also a little misleading. It doesn't try to reset anything, that's reclaim's job.
-- Mel Gorman SUSE Labs
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