From: Vlastimil Babka <vbabka@suse.cz>
To: Michal Hocko <mhocko@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Mel Gorman <mgorman@techsingularity.net>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
David Rientjes <rientjes@google.com>,
Rik van Riel <riel@redhat.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v6 06/11] mm, compaction: more reliably increase direct compaction priority
Date: Thu, 18 Aug 2016 11:44:00 +0200 [thread overview]
Message-ID: <1f761527-ed12-ba16-0565-c64d14e200eb@suse.cz> (raw)
In-Reply-To: <20160818091036.GF30162@dhcp22.suse.cz>
On 08/18/2016 11:10 AM, Michal Hocko wrote:
> On Wed 10-08-16 11:12:21, Vlastimil Babka wrote:
>> During reclaim/compaction loop, compaction priority can be increased by the
>> should_compact_retry() function, but the current code is not optimal. Priority
>> is only increased when compaction_failed() is true, which means that compaction
>> has scanned the whole zone. This may not happen even after multiple attempts
>> with a lower priority due to parallel activity, so we might needlessly
>> struggle on the lower priorities and possibly run out of compaction retry
>> attempts in the process.
>>
>> After this patch we are guaranteed at least one attempt at the highest
>> compaction priority even if we exhaust all retries at the lower priorities.
>
> I expect we will tend to do some special handling at the highest
> priority so guaranteeing at least one run with that prio seems sensible to me. The only
> question is whether we really want to enforce the highest priority for
> costly orders as well. I think we want to reserve the highest (maybe add
> one more) prio for !costly orders as those invoke the OOM killer and the
> failure are quite disruptive.
Costly orders are already ruled out of reaching the highest priority
unless they are __GFP_REPEAT, so I assumed that if they are allocations
with __GFP_REPEAT, they really would like to succeed, so let them use
the highest priority.
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next prev parent reply other threads:[~2016-08-18 9:44 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-10 9:12 [PATCH v6 00/11] make direct compaction more deterministic Vlastimil Babka
2016-08-10 9:12 ` [PATCH v6 01/11] mm, compaction: make whole_zone flag ignore cached scanner positions Vlastimil Babka
2016-08-10 9:12 ` [PATCH v6 02/11] mm, compaction: cleanup unused functions Vlastimil Babka
2016-08-10 9:12 ` [PATCH v6 03/11] mm, compaction: rename COMPACT_PARTIAL to COMPACT_SUCCESS Vlastimil Babka
2016-08-18 9:01 ` Michal Hocko
2016-08-10 9:12 ` [PATCH v6 04/11] mm, compaction: don't recheck watermarks after COMPACT_SUCCESS Vlastimil Babka
2016-08-16 6:12 ` Joonsoo Kim
2016-08-16 6:11 ` Vlastimil Babka
2016-08-18 11:59 ` Vlastimil Babka
2016-08-18 9:03 ` Michal Hocko
2016-08-10 9:12 ` [PATCH v6 05/11] mm, compaction: add the ultimate direct compaction priority Vlastimil Babka
2016-08-16 5:58 ` Joonsoo Kim
2016-08-18 12:23 ` Vlastimil Babka
2016-08-10 9:12 ` [PATCH v6 06/11] mm, compaction: more reliably increase " Vlastimil Babka
2016-08-16 6:07 ` Joonsoo Kim
2016-08-16 6:31 ` Vlastimil Babka
2016-08-18 9:10 ` Michal Hocko
2016-08-18 9:44 ` Vlastimil Babka [this message]
2016-08-18 9:48 ` Michal Hocko
2016-08-10 9:12 ` [PATCH v6 07/11] mm, compaction: use correct watermark when checking compaction success Vlastimil Babka
2016-08-10 9:12 ` [PATCH v6 08/11] mm, compaction: create compact_gap wrapper Vlastimil Babka
2016-08-16 6:15 ` Joonsoo Kim
2016-08-16 6:15 ` Vlastimil Babka
2016-08-16 6:41 ` Joonsoo Kim
2016-08-18 12:13 ` Vlastimil Babka
2016-08-10 9:12 ` [PATCH v6 09/11] mm, compaction: use proper alloc_flags in __compaction_suitable() Vlastimil Babka
2016-08-10 9:12 ` [PATCH v6 10/11] mm, compaction: require only min watermarks for non-costly orders Vlastimil Babka
2016-08-16 6:16 ` Joonsoo Kim
2016-08-16 6:36 ` Vlastimil Babka
2016-08-16 6:46 ` Joonsoo Kim
2016-08-18 12:20 ` Vlastimil Babka
2016-08-10 9:12 ` [PATCH v6 11/11] mm, vmscan: make compaction_ready() more accurate and readable Vlastimil Babka
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