From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f199.google.com (mail-wr0-f199.google.com [209.85.128.199]) by kanga.kvack.org (Postfix) with ESMTP id 4C7976B0038 for ; Wed, 22 Mar 2017 10:44:22 -0400 (EDT) Received: by mail-wr0-f199.google.com with SMTP id u108so40593295wrb.3 for ; Wed, 22 Mar 2017 07:44:22 -0700 (PDT) Received: from gum.cmpxchg.org (gum.cmpxchg.org. [85.214.110.215]) by mx.google.com with ESMTPS id f18si2508312wrc.171.2017.03.22.07.44.20 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 22 Mar 2017 07:44:21 -0700 (PDT) Date: Wed, 22 Mar 2017 10:43:49 -0400 From: Johannes Weiner Subject: Re: [PATCH v5] mm/vmscan: more restrictive condition for retry in do_try_to_free_pages Message-ID: <20170322144349.GA22107@cmpxchg.org> References: <1490191893-5923-1-git-send-email-ysxie@foxmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1490191893-5923-1-git-send-email-ysxie@foxmail.com> Sender: owner-linux-mm@kvack.org List-ID: To: Yisheng Xie 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 On Wed, Mar 22, 2017 at 10:11:33PM +0800, Yisheng Xie wrote: > From: Yisheng Xie > > 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 > Acked-by: Michal Hocko > Suggested-by: Johannes Weiner > Suggested-by: Michal Hocko > Suggested-by: Shakeel Butt > Reviewed-by: Shakeel Butt Acked-by: Johannes Weiner Thanks Yisheng! -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org