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 X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E0AF1C32751 for ; Sat, 10 Aug 2019 21:07:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BFB842166E for ; Sat, 10 Aug 2019 21:07:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726500AbfHJVHw (ORCPT ); Sat, 10 Aug 2019 17:07:52 -0400 Received: from 68.66.241.172.static.a2webhosting.com ([68.66.241.172]:48738 "EHLO vps.redhazel.co.uk" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1725863AbfHJVHw (ORCPT ); Sat, 10 Aug 2019 17:07:52 -0400 Received: from [192.168.1.66] (unknown [212.159.68.143]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by vps.redhazel.co.uk (Postfix) with ESMTPSA id 1E5011C02B32; Sat, 10 Aug 2019 22:07:50 +0100 (BST) Subject: Re: Let's talk about the elephant in the room - the Linux kernel's inability to gracefully handle low memory pressure To: Michal Hocko Cc: Johannes Weiner , Suren Baghdasaryan , Vlastimil Babka , "Artem S. Tashkinov" , Andrew Morton , LKML , linux-mm References: <20190806220150.GA22516@cmpxchg.org> <20190807075927.GO11812@dhcp22.suse.cz> <20190807205138.GA24222@cmpxchg.org> <20190808114826.GC18351@dhcp22.suse.cz> <806F5696-A8D6-481D-A82F-49DEC1F2B035@redhazel.co.uk> <20190808163228.GE18351@dhcp22.suse.cz> <5FBB0A26-0CFE-4B88-A4F2-6A42E3377EDB@redhazel.co.uk> <20190808185925.GH18351@dhcp22.suse.cz> <08e5d007-a41a-e322-5631-b89978b9cc20@redhazel.co.uk> <20190809085748.GN18351@dhcp22.suse.cz> From: ndrw Message-ID: <5fcf237c-d270-26e5-e995-02755695b459@redhazel.co.uk> Date: Sat, 10 Aug 2019 22:07:49 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20190809085748.GN18351@dhcp22.suse.cz> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/08/2019 09:57, Michal Hocko wrote: > This is a useful feedback! What was your workload? Which kernel version? With 16GB zram swap and swappiness=60 I get the avg10 memory PSI numbers of about 10 when swap is half filled and ~30 immediately before the freeze. Swapping with zram has less effect on system responsiveness comparing to swapping to an ssd, so, if combined with the proposed PSI triggered OOM killer, this could be a viable solution. Still, using swap only to make PSI sensing work when triggering OOM killer at non-zero available memory would do the job just as well is a bit of an overkill. I don't really need these extra few GB or memory, just want to get rid of system freezes. Perhaps we could have both heuristics. Best regards, ndrw