From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qc0-f182.google.com (mail-qc0-f182.google.com [209.85.216.182]) by kanga.kvack.org (Postfix) with ESMTP id 2879A6B0032 for ; Mon, 16 Mar 2015 07:43:58 -0400 (EDT) Received: by qcaz10 with SMTP id z10so40472609qca.1 for ; Mon, 16 Mar 2015 04:43:58 -0700 (PDT) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTPS id w33si9631630qgw.43.2015.03.16.04.43.56 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 16 Mar 2015 04:43:57 -0700 (PDT) Message-ID: <5506C1F6.1090803@redhat.com> Date: Mon, 16 Mar 2015 07:43:50 -0400 From: Rik van Riel MIME-Version: 1.0 Subject: Re: kswapd hogging in lowmem_shrink References: <5502F9BC.2020001@redhat.com> In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Vaibhav Shinde Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton , Mel Gorman On 03/16/2015 03:45 AM, Vaibhav Shinde wrote: > > > On Fri, Mar 13, 2015 at 7:52 AM, Rik van Riel > wrote: >> >> On 03/13/2015 10:25 AM, Vaibhav Shinde wrote: >> > >> > On low memory situation, I see various shrinkers being invoked, but in >> > lowmem_shrink() case, kswapd is found to be hogging for around 150msecs. >> > >> > Due to this my application suffer latency issue, as the cpu was not >> > released by kswapd0. >> > >> > I took below traces with vmscan events, that show lowmem_shrink taking >> > such long time for execution. >> >> This is the Android low memory killer, which kills the >> task with the lowest priority in the system. >> >> The low memory killer will iterate over all the tasks >> in the system to identify the task to kill. >> >> This is not a problem in Android systems, and other >> small systems where this piece of code is used. >> >> What kind of system are you trying to use the low >> memory killer on? >> >> How many tasks are you running? >> > yes, lowmemorykiller kills the task depending on its oom_score, I am > using a embedded device with 2GB memory, there are task running that > cause lowmemory situation - no issue about it. > > But my concern is kswapd takes too long to iterate through all the > processes(lowmem_shrink() => for_each_process()), the time taken is > around 150msec, due to which my high priority application suffer system > latency that cause malfunctioning. If it is an issue for you, you will have to fix that. -- All rights reversed -- 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