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Re: [PATCH 4/5] mm: consider per-zone inactive ratio to deactivate

From Johannes Weiner <hannes@cmpxchg.org>
Newsgroups linux.kernel
Subject Re: [PATCH 4/5] mm: consider per-zone inactive ratio to deactivate
Date 2016-07-21 18:00 +0200
Message-ID <rXoye-107-11@gated-at.bofh.it> (permalink)
References <rXmZs-8w7-5@gated-at.bofh.it> <rXmZs-8w7-15@gated-at.bofh.it>
Organization linux.* mail to news gateway

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On Thu, Jul 21, 2016 at 03:11:00PM +0100, Mel Gorman wrote:
> @@ -1981,6 +1982,32 @@ static bool inactive_list_is_low(struct lruvec *lruvec, bool file)
>  	inactive = lruvec_lru_size(lruvec, file * LRU_FILE);
>  	active = lruvec_lru_size(lruvec, file * LRU_FILE + LRU_ACTIVE);
>  
> +	/*
> +	 * For global reclaim on zone-constrained allocations, it is necessary
> +	 * to check if rotations are required for lowmem to be reclaimed. This

s/rotation/deactivation/

> +	 * calculates the inactive/active pages available in eligible zones.
> +	 */
> +	if (global_reclaim(sc)) {
> +		struct pglist_data *pgdat = lruvec_pgdat(lruvec);
> +		int zid;
> +
> +		for (zid = sc->reclaim_idx + 1; zid < MAX_NR_ZONES; zid++) {

The emphasis on global vs. memcg reclaim is somewhat strange, because
this is only about excluding pages from the balancing math that will
be skipped. Memcg reclaim is never zone-restricted, but if it were, it
would make sense to exclude the skipped pages there as well.

Indeed, for memcg reclaim sc->reclaim_idx+1 is always MAX_NR_ZONES,
and so the for loop alone will do the right thing.

Can you please drop the global_reclaim() branch, the sc function
parameter, and the "global reclaim" from the comment?

Thanks

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Thread

[PATCH 0/5] Candidate fixes for premature OOM kills with node-lru v2 Mel Gorman <mgorman@techsingularity.net> - 2016-07-21 16:20 +0200
  [PATCH 4/5] mm: consider per-zone inactive ratio to deactivate Mel Gorman <mgorman@techsingularity.net> - 2016-07-21 16:20 +0200
    Re: [PATCH 4/5] mm: consider per-zone inactive ratio to deactivate Johannes Weiner <hannes@cmpxchg.org> - 2016-07-21 18:00 +0200
  [PATCH 1/5] mm: add per-zone lru list stat Mel Gorman <mgorman@techsingularity.net> - 2016-07-21 16:20 +0200
    Re: [PATCH 1/5] mm: add per-zone lru list stat Johannes Weiner <hannes@cmpxchg.org> - 2016-07-22 18:00 +0200

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