From: Andrew Morton <akpm@linux-foundation.org>
To: Mel Gorman <mgorman@suse.de>
Cc: Leon Romanovsky <leon@leon.nu>, Vlastimil Babka <vbabka@suse.cz>,
Johannes Weiner <hannes@cmpxchg.org>,
Linux Kernel <linux-kernel@vger.kernel.org>,
Linux-MM <linux-mm@kvack.org>,
Linux-FSDevel <linux-fsdevel@vger.kernel.org>
Subject: Re: [PATCH] mm: page_alloc: Fix setting of ZONE_FAIR_DEPLETED on UP v2
Date: Tue, 9 Sep 2014 12:53:18 -0700 [thread overview]
Message-ID: <20140909125318.b07aee9f77b5a15d6b3041f1@linux-foundation.org> (raw)
In-Reply-To: <20140908115718.GL17501@suse.de>
On Mon, 8 Sep 2014 12:57:18 +0100 Mel Gorman <mgorman@suse.de> wrote:
> zone_page_state is an API hazard because of the difference in behaviour
> between SMP and UP is very surprising. There is a good reason to allow
> NR_ALLOC_BATCH to go negative -- when the counter is reset the negative
> value takes recent activity into account. This patch makes zone_page_state
> behave the same on SMP and UP as saving one branch on UP is not likely to
> make a measurable performance difference.
>
> ...
>
> --- a/include/linux/vmstat.h
> +++ b/include/linux/vmstat.h
> @@ -131,10 +131,8 @@ static inline unsigned long zone_page_state(struct zone *zone,
> enum zone_stat_item item)
> {
> long x = atomic_long_read(&zone->vm_stat[item]);
> -#ifdef CONFIG_SMP
> if (x < 0)
> x = 0;
> -#endif
> return x;
> }
We now have three fixes for the same thing. I'm presently holding on
to hannes's mm-page_alloc-fix-zone-allocation-fairness-on-up.patch.
Regularizing zone_page_state() in this fashion seems a good idea and is
presumably safe because callers have been tested with SMP. So unless
shouted at I think I'll queue this one for 3.18?
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next prev parent reply other threads:[~2014-09-09 19:53 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-07-09 8:13 [PATCH 0/5] Reduce sequential read overhead Mel Gorman
2014-07-09 8:13 ` [PATCH 1/6] mm: pagemap: Avoid unnecessary overhead when tracepoints are deactivated Mel Gorman
2014-07-10 12:01 ` Johannes Weiner
2014-07-09 8:13 ` [PATCH 2/6] mm: Rearrange zone fields into read-only, page alloc, statistics and page reclaim lines Mel Gorman
2014-07-10 12:06 ` Johannes Weiner
2014-07-09 8:13 ` [PATCH 3/6] mm: Move zone->pages_scanned into a vmstat counter Mel Gorman
2014-07-10 12:08 ` Johannes Weiner
2014-07-09 8:13 ` [PATCH 4/6] mm: vmscan: Only update per-cpu thresholds for online CPU Mel Gorman
2014-07-10 12:09 ` Johannes Weiner
2014-07-09 8:13 ` [PATCH 5/6] mm: page_alloc: Abort fair zone allocation policy when remotes nodes are encountered Mel Gorman
2014-07-10 12:14 ` Johannes Weiner
2014-07-10 12:44 ` Mel Gorman
2014-07-09 8:13 ` [PATCH 6/6] mm: page_alloc: Reduce cost of the fair zone allocation policy Mel Gorman
2014-07-10 12:18 ` Johannes Weiner
2014-08-08 15:27 ` Vlastimil Babka
2014-08-11 12:12 ` Mel Gorman
2014-08-11 12:34 ` Vlastimil Babka
2014-09-02 14:01 ` Johannes Weiner
2014-09-05 10:14 ` [PATCH] mm: page_alloc: Fix setting of ZONE_FAIR_DEPLETED on UP Mel Gorman
2014-09-07 6:32 ` Leon Romanovsky
2014-09-08 11:57 ` [PATCH] mm: page_alloc: Fix setting of ZONE_FAIR_DEPLETED on UP v2 Mel Gorman
2014-09-09 8:17 ` Leon Romanovsky
2014-09-09 19:53 ` Andrew Morton [this message]
2014-09-10 9:16 ` Mel Gorman
2014-09-10 20:32 ` Johannes Weiner
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