From: Minchan Kim <minchan@kernel.org>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Mel Gorman <mgorman@techsingularity.net>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Sangseok Lee <sangseok.lee@lge.com>
Subject: Re: [PATCH 1/4] mm: adjust reserved highatomic count
Date: Tue, 11 Oct 2016 13:19:16 +0900 [thread overview]
Message-ID: <20161011041916.GA30973@bbox> (raw)
In-Reply-To: <c0920ac2-fe63-567e-e24c-eb6d638143b0@suse.cz>
Hi Vlasimil,
On Mon, Oct 10, 2016 at 08:57:40AM +0200, Vlastimil Babka wrote:
> On 10/07/2016 04:29 PM, Minchan Kim wrote:
> >>>In that case, we should adjust nr_reserved_highatomic.
> >>>Otherwise, VM cannot reserve highorderatomic pageblocks any more
> >>>although it doesn't reach 1% limit. It means highorder atomic
> >>>allocation failure would be higher.
> >>>
> >>>So, this patch decreases the account as well as migratetype
> >>>if it was MIGRATE_HIGHATOMIC.
> >>>
> >>>Signed-off-by: Minchan Kim <minchan@kernel.org>
> >>
> >>Hm wouldn't it be simpler just to prevent the pageblock's migratetype to be
> >>changed if it's highatomic? Possibly also not do move_freepages_block() in
> >
> >It could be. Actually, I did it with modifying can_steal_fallback which returns
> >false it found the pageblock is highorderatomic but changed to this way again
> >because I don't have any justification to prevent changing pageblock.
> >If you give concrete justification so others isn't against on it, I am happy to
> >do what you suggested.
>
> Well, MIGRATE_HIGHATOMIC is not listed in the fallbacks array at all, so we
> are not supposed to steal from it in the first place. Stealing will only
> happen due to races, which would be too costly to close, so we allow them
> and expect to be rare. But we shouldn't allow them to break the accounting.
>
Fair enough.
How about this?
next prev parent reply other threads:[~2016-10-11 4:19 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-07 5:45 [PATCH 0/4] use up highorder free pages before OOM Minchan Kim
2016-10-07 5:45 ` [PATCH 1/4] mm: adjust reserved highatomic count Minchan Kim
2016-10-07 12:30 ` Vlastimil Babka
2016-10-07 14:29 ` Minchan Kim
2016-10-10 6:57 ` Vlastimil Babka
2016-10-11 4:19 ` Minchan Kim [this message]
2016-10-11 9:40 ` Vlastimil Babka
2016-10-12 5:36 ` Mel Gorman
2016-10-07 5:45 ` [PATCH 2/4] mm: prevent double decrease of nr_reserved_highatomic Minchan Kim
2016-10-07 12:44 ` Vlastimil Babka
2016-10-07 14:30 ` Minchan Kim
2016-10-12 5:36 ` Mel Gorman
2016-10-07 5:45 ` [PATCH 3/4] mm: unreserve highatomic free pages fully before OOM Minchan Kim
2016-10-07 9:09 ` Michal Hocko
2016-10-07 14:43 ` Minchan Kim
2016-10-10 7:41 ` Michal Hocko
2016-10-11 5:01 ` Minchan Kim
2016-10-11 6:50 ` Michal Hocko
2016-10-11 7:09 ` Minchan Kim
2016-10-11 7:26 ` Michal Hocko
2016-10-11 7:37 ` Minchan Kim
2016-10-11 8:01 ` Michal Hocko
2016-10-07 5:45 ` [PATCH 4/4] mm: skip to reserve pageblock crossed zone boundary for HIGHATOMIC Minchan Kim
2016-10-07 9:16 ` [PATCH 0/4] use up highorder free pages before OOM Michal Hocko
2016-10-07 15:04 ` Minchan Kim
2016-10-10 7:47 ` Michal Hocko
2016-10-11 5:06 ` Minchan Kim
2016-10-11 6:53 ` Michal Hocko
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