From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CEEDFC433EF for ; Fri, 15 Oct 2021 20:01:39 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 7D8BC61164 for ; Fri, 15 Oct 2021 20:01:39 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 7D8BC61164 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id E6EEF6B006C; Fri, 15 Oct 2021 16:01:38 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id E1DC16B0072; Fri, 15 Oct 2021 16:01:38 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D5A49900002; Fri, 15 Oct 2021 16:01:38 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0093.hostedemail.com [216.40.44.93]) by kanga.kvack.org (Postfix) with ESMTP id CA0786B006C for ; Fri, 15 Oct 2021 16:01:38 -0400 (EDT) Received: from smtpin33.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 7C6702D4A4 for ; Fri, 15 Oct 2021 20:01:38 +0000 (UTC) X-FDA: 78699741876.33.35F16F1 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf13.hostedemail.com (Postfix) with ESMTP id AF1321042126 for ; Fri, 15 Oct 2021 20:00:36 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id F322761151; Fri, 15 Oct 2021 20:00:36 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1634328037; bh=7V/+1FW4XJaY4Tukrc6cjuQq0Lv0qT3qHWJvILfbP8k=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=tqe6f2Zi5ekP1KVx7FMNoH7GFR2U4AgdYRjpf3rZuEm4kQNWYzvQF0A0m1Mlay9jC ANkaEsNGpddWaZG3ccXGMm+XI+vwIfnBHWjdf8+RQnrbq6m2xOwJfK35WK5UuFR4pm C8DjIm073AXHW7eZJ2T6Fou7k1V1C0MlziFEReU4= Date: Fri, 15 Oct 2021 13:00:35 -0700 From: Andrew Morton To: Huangzhaoyang Cc: Johannes Weiner , Michal Hocko , Vladimir Davydov , Zhaoyang Huang , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm: skip current when memcg reclaim Message-Id: <20211015130035.aacc18a4d1ee141b306c2272@linux-foundation.org> In-Reply-To: <1634278529-16983-1-git-send-email-huangzhaoyang@gmail.com> References: <1634278529-16983-1-git-send-email-huangzhaoyang@gmail.com> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: AF1321042126 X-Stat-Signature: xu7911a3gtfst9uj81y4g1qajwxkgxqk Authentication-Results: imf13.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=tqe6f2Zi; spf=pass (imf13.hostedemail.com: domain of akpm@linux-foundation.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org; dmarc=none X-HE-Tag: 1634328036-655365 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, 15 Oct 2021 14:15:29 +0800 Huangzhaoyang wrote: > From: Zhaoyang Huang > > Sibling thread of the same process could refault the reclaimed pages > in the same time, which would be typical in None global reclaim and > introduce thrashing. "None" -> "node", I assume? > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -2841,6 +2841,11 @@ static void shrink_node_memcgs(pg_data_t *pgdat, struct scan_control *sc) > sc->memcg_low_skipped = 1; > continue; > } > + /* > + * Don't bother current when its memcg is below low > + */ The comment explains what the code is doing, but the code itself already does this. Please can we have a comment that explains *why* the code is doing this? > + if (get_mem_cgroup_from_mm(current->mm) == memcg) > + continue; > memcg_memory_event(memcg, MEMCG_LOW); > }