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From: Mike Kravetz <mike.kravetz@oracle.com>
To: Vlastimil Babka <vbabka@suse.cz>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org
Cc: Hillf Danton <hdanton@sina.com>, Michal Hocko <mhocko@kernel.org>,
	Mel Gorman <mgorman@suse.de>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Andrea Arcangeli <aarcange@redhat.com>,
	David Rientjes <rientjes@google.com>,
	Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH 1/3] mm, reclaim: make should_continue_reclaim perform dryrun detection
Date: Mon, 5 Aug 2019 09:54:45 -0700	[thread overview]
Message-ID: <e2252a42-063a-8f34-c300-9250d783b2fb@oracle.com> (raw)
In-Reply-To: <bb16d3f0-0984-be32-4346-358abad92c4c@suse.cz>

On 8/5/19 1:42 AM, Vlastimil Babka wrote:
> On 8/3/19 12:39 AM, Mike Kravetz wrote:
>> From: Hillf Danton <hdanton@sina.com>
>>
>> Address the issue of should_continue_reclaim continuing true too often
>> for __GFP_RETRY_MAYFAIL attempts when !nr_reclaimed and nr_scanned.
>> This could happen during hugetlb page allocation causing stalls for
>> minutes or hours.
>>
>> We can stop reclaiming pages if compaction reports it can make a progress.
>> A code reshuffle is needed to do that.
> 
>> And it has side-effects, however,
>> with allocation latencies in other cases but that would come at the cost
>> of potential premature reclaim which has consequences of itself.
> 
> Based on Mel's longer explanation, can we clarify the wording here? e.g.:
> 
> There might be side-effect for other high-order allocations that would
> potentially benefit from more reclaim before compaction for them to be
> faster and less likely to stall, but the consequences of
> premature/over-reclaim are considered worse.
> 
>> We can also bail out of reclaiming pages if we know that there are not
>> enough inactive lru pages left to satisfy the costly allocation.
>>
>> We can give up reclaiming pages too if we see dryrun occur, with the
>> certainty of plenty of inactive pages. IOW with dryrun detected, we are
>> sure we have reclaimed as many pages as we could.
>>
>> Cc: Mike Kravetz <mike.kravetz@oracle.com>
>> Cc: Mel Gorman <mgorman@suse.de>
>> Cc: Michal Hocko <mhocko@kernel.org>
>> Cc: Vlastimil Babka <vbabka@suse.cz>
>> Cc: Johannes Weiner <hannes@cmpxchg.org>
>> Signed-off-by: Hillf Danton <hdanton@sina.com>
>> Tested-by: Mike Kravetz <mike.kravetz@oracle.com>
>> Acked-by: Mel Gorman <mgorman@suse.de>
> 
> Acked-by: Vlastimil Babka <vbabka@suse.cz>
> I will send some followup cleanup.
> 
> There should be also Mike's SOB?

Will do.
My apologies, the process of handling patches created by others is new
to me.

Also, will incorporate Mel's explanation.
-- 
Mike Kravetz

  parent reply	other threads:[~2019-08-05 16:55 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-02 22:39 [PATCH 0/3] address hugetlb page allocation stalls Mike Kravetz
2019-08-02 22:39 ` [PATCH 1/3] mm, reclaim: make should_continue_reclaim perform dryrun detection Mike Kravetz
2019-08-05  8:42   ` Vlastimil Babka
2019-08-05 10:57     ` Vlastimil Babka
2019-08-05 16:58       ` Mike Kravetz
2019-08-05 18:34         ` Vlastimil Babka
2019-08-05 16:54     ` Mike Kravetz [this message]
2019-08-02 22:39 ` [PATCH 2/3] mm, compaction: raise compaction priority after it withdrawns Mike Kravetz
2019-08-05  9:14   ` Vlastimil Babka
2019-08-02 22:39 ` [PATCH 3/3] hugetlbfs: don't retry when pool page allocations start to fail Mike Kravetz
2019-08-05  9:28   ` Vlastimil Babka
2019-08-05 17:12     ` Mike Kravetz

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