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=-0.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 93390C4BA06 for ; Wed, 26 Feb 2020 02:51:34 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 2C03924653 for ; Wed, 26 Feb 2020 02:51:33 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="qu/zSUYO" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2C03924653 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=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 87E316B0003; Tue, 25 Feb 2020 21:51:33 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 810966B0005; Tue, 25 Feb 2020 21:51:33 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 71BFD6B0006; Tue, 25 Feb 2020 21:51:33 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0056.hostedemail.com [216.40.44.56]) by kanga.kvack.org (Postfix) with ESMTP id 561F76B0003 for ; Tue, 25 Feb 2020 21:51:33 -0500 (EST) Received: from smtpin30.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 0D48C180AD807 for ; Wed, 26 Feb 2020 02:51:33 +0000 (UTC) X-FDA: 76530752466.30.shirt18_47a6c7f6a6b16 X-HE-Tag: shirt18_47a6c7f6a6b16 X-Filterd-Recvd-Size: 2999 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf41.hostedemail.com (Postfix) with ESMTP for ; Wed, 26 Feb 2020 02:51:32 +0000 (UTC) Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 0FBD921744; Wed, 26 Feb 2020 02:51:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1582685491; bh=OUGcqtr3slwiFA2R7LCmSyIH96FefNBvDVOEGJkbPG4=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=qu/zSUYOAQ9tXmWzOgoLPNgBh1WuBbX/46dvRHNsTu81c7I0agKHdUsithrjlsFXl /Sh3Tisnq1oz0Z+eEypyOYd4mLgcZeSQaTNjChNVbgO3MrICxDHKLkFDXmSL5DdRFC NRxCk7NAsxOwTkkN0myj3r+mrSNdhhOrNdriPR/8= Date: Tue, 25 Feb 2020 18:51:30 -0800 From: Andrew Morton To: Mel Gorman Cc: Michal Hocko , Vlastimil Babka , Ivan Babrou , Rik van Riel , Linux-MM , Linux Kernel Mailing List Subject: Re: [PATCH 0/3] Limit runaway reclaim due to watermark boosting Message-Id: <20200225185130.6a32a8a6920d11b4c098e90e@linux-foundation.org> In-Reply-To: <20200225141534.5044-1-mgorman@techsingularity.net> References: <20200225141534.5044-1-mgorman@techsingularity.net> 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-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 Tue, 25 Feb 2020 14:15:31 +0000 Mel Gorman wrote: > Ivan Babrou reported the following http://lkml.kernel.org/r/CABWYdi1eOUD1DHORJxTsWPMT3BcZhz++xP1pXhT=x4SgxtgQZA@mail.gmail.com is helpful. > Commit 1c30844d2dfe ("mm: reclaim small amounts of memory when > an external fragmentation event occurs") introduced undesired > effects in our environment. > > * NUMA with 2 x CPU > * 128GB of RAM > * THP disabled > * Upgraded from 4.19 to 5.4 > > Before we saw free memory hover at around 1.4GB with no > spikes. After the upgrade we saw some machines decide that they > need a lot more than that, with frequent spikes above 10GB, > often only on a single numa node. > > There have been a few reports recently that might be watermark boost > related. Unfortunately, finding someone that can reproduce the problem > and test a patch has been problematic. This series intends to limit > potential damage only. It's problematic that we don't understand what's happening. And these palliatives can only reduce our ability to do that. Rik seems to have the means to reproduce this (or something similar) and it seems Ivan can test patches three weeks hence. So how about a debug patch which will help figure out what's going on in there?