From: Johannes Weiner <hannes@cmpxchg.org>
To: Yisheng Xie <ysxie@foxmail.com>
Cc: akpm@linux-foundation.org, mgorman@suse.de, vbabka@suse.cz,
mhocko@suse.com, riel@redhat.com, shakeelb@google.com,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
xieyisheng1@huawei.com, guohanjun@huawei.com,
qiuxishi@huawei.com
Subject: Re: [PATCH v5] mm/vmscan: more restrictive condition for retry in do_try_to_free_pages
Date: Wed, 22 Mar 2017 10:43:49 -0400 [thread overview]
Message-ID: <20170322144349.GA22107@cmpxchg.org> (raw)
In-Reply-To: <1490191893-5923-1-git-send-email-ysxie@foxmail.com>
On Wed, Mar 22, 2017 at 10:11:33PM +0800, Yisheng Xie wrote:
> From: Yisheng Xie <xieyisheng1@huawei.com>
>
> By reviewing code, I find that when enter do_try_to_free_pages, the
> may_thrash is always clear, and it will retry shrink zones to tap
> cgroup's reserves memory by setting may_thrash when the former
> shrink_zones reclaim nothing.
>
> However, when memcg is disabled or on legacy hierarchy, or there do not
> have any memcg protected by low limit, it should not do this useless
> retry at all, for we do not have any cgroup's reserves memory to tap,
> and we have already done hard work but made no progress, which as Michal
> pointed out in former version, we are trying hard to control the retry
> logical of page alloctor, and the current additional round of reclaim is
> just lame.
>
> Therefore, to avoid this unneeded retrying and make code more readable,
> we remove the may_thrash field in scan_control, instead, introduce
> memcg_low_reclaim and memcg_low_skipped, and only retry when
> memcg_low_skipped, by setting memcg_low_reclaim.
>
> Signed-off-by: Yisheng Xie <xieyisheng1@huawei.com>
> Acked-by: Michal Hocko <mhocko@suse.com>
> Suggested-by: Johannes Weiner <hannes@cmpxchg.org>
> Suggested-by: Michal Hocko <mhocko@kernel.org>
> Suggested-by: Shakeel Butt <shakeelb@google.com>
> Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Thanks Yisheng!
next prev parent reply other threads:[~2017-03-22 14:44 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-22 14:11 [PATCH v5] mm/vmscan: more restrictive condition for retry in do_try_to_free_pages Yisheng Xie
2017-03-22 14:43 ` Johannes Weiner [this message]
2017-03-22 14:54 ` Michal Hocko
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