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From: Vlastimil Babka <vbabka@suse.cz>
To: Rik van Riel <riel@surriel.com>, hughd@google.com
Cc: xuyu@linux.alibaba.com, akpm@linux-foundation.org,
	mgorman@suse.de, aarcange@redhat.com, willy@infradead.org,
	linux-kernel@vger.kernel.org, kernel-team@fb.com,
	linux-mm@kvack.org, mhocko@suse.com
Subject: Re: [PATCH 1/3] mm,thp,shmem: limit shmem THP alloc gfp_mask
Date: Thu, 26 Nov 2020 17:56:47 +0100	[thread overview]
Message-ID: <18cea0b2-1037-3276-1d42-2a4adcc129e4@suse.cz> (raw)
In-Reply-To: <20201124194925.623931-2-riel@surriel.com>

On 11/24/20 8:49 PM, Rik van Riel wrote:
> The allocation flags of anonymous transparent huge pages can be controlled
> through the files in /sys/kernel/mm/transparent_hugepage/defrag, which can
> help the system from getting bogged down in the page reclaim and compaction
> code when many THPs are getting allocated simultaneously.
> 
> However, the gfp_mask for shmem THP allocations were not limited by those
> configuration settings, and some workloads ended up with all CPUs stuck
> on the LRU lock in the page reclaim code, trying to allocate dozens of
> THPs simultaneously.
> 
> This patch applies the same configurated limitation of THPs to shmem
> hugepage allocations, to prevent that from happening.
> 
> Controlling the gfp_mask of THP allocations through the knobs in
> sysfs allows users to determine the balance between how aggressively
> the system tries to allocate THPs at fault time, and how much the
> application may end up stalling attempting those allocations.
> 
> This way a THP defrag setting of "never" or "defer+madvise" will result
> in quick allocation failures without direct reclaim when no 2MB free
> pages are available.
> 
> With this patch applied, THP allocations for tmpfs will be a little
> more aggressive than today for files mmapped with MADV_HUGEPAGE,
> and a little less aggressive for files that are not mmapped or
> mapped without that flag.
> 
> Signed-off-by: Rik van Riel <riel@surriel.com>

Acked-by: Vlastimil Babka <vbabka@suse.cz>

  reply	other threads:[~2020-11-26 16:56 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-24 19:49 [PATCH v6 0/3] mm,thp,shm: limit shmem THP alloc gfp_mask Rik van Riel
2020-11-24 19:49 ` [PATCH 1/3] mm,thp,shmem: " Rik van Riel
2020-11-26 16:56   ` Vlastimil Babka [this message]
2020-11-27  8:15   ` Michal Hocko
2020-11-24 19:49 ` [PATCH 2/3] mm,thp,shm: limit gfp mask to no more than specified Rik van Riel
2020-11-26 13:40   ` Michal Hocko
2020-11-26 18:04     ` Rik van Riel
2020-11-26 18:04       ` Rik van Riel
2020-11-27  7:52       ` Michal Hocko
2020-11-27 19:03         ` Rik van Riel
2020-11-27 19:03           ` Rik van Riel
2020-11-30 10:00           ` Michal Hocko
2020-11-30 14:40             ` Rik van Riel
2020-11-30 14:40               ` Rik van Riel
2020-11-24 19:49 ` [PATCH 3/3] mm,thp,shmem: make khugepaged obey tmpfs mount flags Rik van Riel
2020-11-26 17:18   ` Vlastimil Babka
2020-11-26 18:14     ` Rik van Riel
2020-11-26 18:14       ` Rik van Riel
2020-11-26 19:42       ` Vlastimil Babka
2020-11-26 20:14         ` Rik van Riel
2020-11-26 20:14           ` Rik van Riel
2020-12-14 21:16 ` [PATCH v6 0/3] mm,thp,shm: limit shmem THP alloc gfp_mask Hugh Dickins
2020-12-14 21:16   ` Hugh Dickins
2020-12-14 22:20   ` Andrew Morton
2020-12-14 22:52   ` Vlastimil Babka
2021-02-24  8:41     ` Hugh Dickins
2021-02-24  8:41       ` Hugh Dickins
2021-02-24 14:46       ` Rik van Riel
2021-02-24 14:46         ` Rik van Riel
2021-02-24 16:55         ` Hugh Dickins
2021-02-24 16:55           ` Hugh Dickins
2021-02-24 17:10           ` [PATCH 4/3] mm,shmem,thp: limit shmem THP allocations to requested zones Rik van Riel
2021-02-26 12:34             ` Vlastimil Babka

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