From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f199.google.com (mail-pf0-f199.google.com [209.85.192.199]) by kanga.kvack.org (Postfix) with ESMTP id D98F56B046D for ; Sun, 12 Mar 2017 06:17:23 -0400 (EDT) Received: by mail-pf0-f199.google.com with SMTP id w189so245625943pfb.4 for ; Sun, 12 Mar 2017 03:17:23 -0700 (PDT) Received: from smtpbg.qq.com (SMTPBG354.QQ.COM. [59.37.110.87]) by mx.google.com with ESMTPS id w5si8419642pgo.121.2017.03.12.03.17.22 for (version=TLS1 cipher=AES128-SHA bits=128/128); Sun, 12 Mar 2017 03:17:22 -0700 (PDT) Subject: Re: [PATCH v2 RFC] mm/vmscan: more restrictive condition for retry in do_try_to_free_pages References: <1489240264-3290-1-git-send-email-ysxie@foxmail.com> From: Yisheng Xie Message-ID: <58C51FA9.4000705@foxmail.com> Date: Sun, 12 Mar 2017 18:15:05 +0800 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Shakeel Butt Cc: Andrew Morton , Johannes Weiner , Mel Gorman , Vlastimil Babka , Michal Hocko , riel@redhat.com, Linux MM , LKML , xieyisheng1@huawei.com, guohanjun@huawei.com, Xishi Qiu hi, Shakeel, On 03/12/2017 01:52 AM, Shakeel Butt wrote: > On Sat, Mar 11, 2017 at 5:51 AM, Yisheng Xie wrote: >> From: Yisheng Xie >> >> When we 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, 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. >> >> To avoid this time costly and useless retrying, add a stub function >> may_thrash and return true when memcg is disabled or on legacy >> hierarchy. >> >> Signed-off-by: Yisheng Xie >> Suggested-by: Shakeel Butt >> --- >> >> return 1; >> >> /* Untapped cgroup reserves? Don't OOM, retry. */ >> - if (!sc->may_thrash) { >> + if (!may_thrash(sc)) { > Thanks Yisheng. The name of the function may_thrash() is confusing in > the sense that it is returning exactly the opposite of what its name > implies. Right. > How about reversing the condition of may_thrash() function > and change the scan_control's field may_thrash to thrashed? hmm, maybe I can change the may_thrash() function to mem_cgroup_thrashed(). For, if change the scan_control's may_thrash to thrashed, it may also looks confusing in shrink_node, and it will be like: if (mem_cgroup_low(root, memcg)) { if (!sc->thrashed) -----> looks confuse here? continue; mem_cgroup_events(memcg, MEMCG_LOW, 1); } Thanks Yisheng Xie @ -- 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