From: Mel Gorman <mgorman@techsingularity.net>
To: Jia He <hejianet@gmail.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
Vlastimil Babka <vbabka@suse.cz>, Michal Hocko <mhocko@suse.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Taku Izumi <izumi.taku@jp.fujitsu.com>
Subject: Re: [PATCH RFC 1/1] mm, page_alloc: fix incorrect zone_statistics data
Date: Tue, 20 Dec 2016 12:31:22 +0000 [thread overview]
Message-ID: <20161220123121.e4wgkxm2txdoxogo@techsingularity.net> (raw)
In-Reply-To: <1481522347-20393-2-git-send-email-hejianet@gmail.com>
On Mon, Dec 12, 2016 at 01:59:07PM +0800, Jia He wrote:
> In commit b9f00e147f27 ("mm, page_alloc: reduce branches in
> zone_statistics"), it reconstructed codes to reduce the branch miss rate.
> Compared with the original logic, it assumed if !(flag & __GFP_OTHER_NODE)
> z->node would not be equal to preferred_zone->node. That seems to be
> incorrect.
>
> Fixes: commit b9f00e147f27 ("mm, page_alloc: reduce branches in
> zone_statistics")
>
> Signed-off-by: Jia He <hejianet@gmail.com>
This is slightly curious. It appear it would only occur if a process was
running on a node that was outside the memory policy. Can you confirm
that is the case?
If so, your patch is a a semantic curiousity because it's actually
impossible for a NUMA allocation to be local and the definition of "HIT"
is fuzzy enough to be useless.
I won't object to the patch but it makes me trust "hit" even less than I
already do for any analysis.
Note that after this mail that I'll be unavailable by mail until early
new years.
--
Mel Gorman
SUSE Labs
next prev parent reply other threads:[~2016-12-20 12:31 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-12 5:59 [PATCH RFC 0/1] mm, page_alloc: fix incorrect zone_statistics data Jia He
2016-12-12 5:59 ` [PATCH RFC 1/1] " Jia He
2016-12-20 9:18 ` Michal Hocko
2016-12-20 13:10 ` Mel Gorman
2016-12-20 13:26 ` Michal Hocko
2016-12-20 14:28 ` Mel Gorman
2016-12-20 14:35 ` Michal Hocko
2016-12-20 14:49 ` Vlastimil Babka
2016-12-20 14:54 ` Mel Gorman
2016-12-21 7:57 ` Michal Hocko
2016-12-20 14:42 ` Mel Gorman
2016-12-20 15:13 ` Vlastimil Babka
2016-12-21 3:01 ` hejianet
2016-12-20 12:31 ` Mel Gorman [this message]
2016-12-21 3:07 ` hejianet
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