From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f44.google.com (mail-pa0-f44.google.com [209.85.220.44]) by kanga.kvack.org (Postfix) with ESMTP id 61A33828F2 for ; Wed, 2 Mar 2016 09:21:28 -0500 (EST) Received: by mail-pa0-f44.google.com with SMTP id a9so12056097pat.3 for ; Wed, 02 Mar 2016 06:21:28 -0800 (PST) Received: from smtpbg302.qq.com (smtpbg302.qq.com. [184.105.206.27]) by mx.google.com with ESMTPS id 65si58495954pfc.6.2016.03.02.06.21.27 for (version=TLS1 cipher=AES128-SHA bits=128/128); Wed, 02 Mar 2016 06:21:27 -0800 (PST) Subject: Re: kswapd consumes 100% CPU when highest zone is small References: From: chen feng Message-ID: <56D6F6D7.50103@foxmail.com> Date: Wed, 2 Mar 2016 22:21:11 +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: Jerry Lee , linux-mm@kvack.org, puck.chen@huawei.com On 2016/3/2 14:20, Jerry Lee wrote: > Hi, > > I have a x86_64 system with 2G RAM using linux-3.12.x. During copying > large > files (e.g. 100GB), kswapd easily consumes 100% CPU until the file is > deleted > or the page cache is dropped. With setting the min_free_kbytes from 16384 > to > 65536, the symptom is mitigated but I can't totally get rid of the problem. > > After some trial and error, I found that highest zone is always unbalanced > with > order-0 page request so that pgdat_blanaced() continuously return false and > kswapd can't sleep. > > Here's the watermarks (min_free_kbytes = 65536) in my system: > Node 0, zone DMA > pages free 2167 > min 138 > low 172 > high 207 > scanned 0 > spanned 4095 > present 3996 > managed 3974 > > Node 0, zone DMA32 > pages free 215375 > min 16226 > low 20282 > high 24339 > scanned 0 > spanned 1044480 > present 490971 > managed 464223 > > Node 0, zone Normal > pages free 7 > min 18 > low 22 > high 27 > scanned 0 > spanned 1536 > present 1536 > managed 523 > > Besides, when the kswapd crazily spins, the value of the following entries > in vmstat increases quickly even when I stop copying file: > > pgalloc_dma 17719 > pgalloc_dma32 3262823 > slabs_scanned 937728 > kswapd_high_wmark_hit_quickly 54333233 > pageoutrun 54333235 > > Is there anything I could do to totally get rid of the problem? > \ Yes, I have the same issue on arm64 platform. I think you can increase the normal ZONE size. And I think there will be a memory alloc process in your system which tigger the kswapd too frequently. You can set this process to no-kswapd flag will also solve this issue. > Thanks > -- 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