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=-5.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 B9BABC2BA83 for ; Fri, 7 Feb 2020 22:54:56 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 772A022464 for ; Fri, 7 Feb 2020 22:54:56 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=cloudflare.com header.i=@cloudflare.com header.b="yuMv4j/S" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 772A022464 Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=cloudflare.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 26B7D6B0003; Fri, 7 Feb 2020 17:54:56 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 241906B000A; Fri, 7 Feb 2020 17:54:56 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 17EF56B000C; Fri, 7 Feb 2020 17:54:56 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0154.hostedemail.com [216.40.44.154]) by kanga.kvack.org (Postfix) with ESMTP id 01DBC6B0003 for ; Fri, 7 Feb 2020 17:54:55 -0500 (EST) Received: from smtpin25.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id A56082C04 for ; Fri, 7 Feb 2020 22:54:55 +0000 (UTC) X-FDA: 76464837750.25.wish20_ddefc4983f19 X-HE-Tag: wish20_ddefc4983f19 X-Filterd-Recvd-Size: 3536 Received: from mail-qt1-f194.google.com (mail-qt1-f194.google.com [209.85.160.194]) by imf02.hostedemail.com (Postfix) with ESMTP for ; Fri, 7 Feb 2020 22:54:55 +0000 (UTC) Received: by mail-qt1-f194.google.com with SMTP id l19so661496qtq.8 for ; Fri, 07 Feb 2020 14:54:55 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cloudflare.com; s=google; h=mime-version:from:date:message-id:subject:to:cc; bh=IbED31rDsq1pztcDA0AbIYB2zqHtiu3fIIwDDgr0ROY=; b=yuMv4j/SoDlOxhbmiBXl97vV364eVGy//UWz/P9YnSkF3WAVAjI/1GSibRYMISOOy9 JfeHiTEkEC94dVrnFb8lyXpsNvmYm2pSbKYjpwsQi71hVfT0m4gkm/f57CQbdYj7c6Ee 9wwkBfyL7fxUi0/bDy77SlN9uRFoVmm+a+TPU= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:from:date:message-id:subject:to:cc; bh=IbED31rDsq1pztcDA0AbIYB2zqHtiu3fIIwDDgr0ROY=; b=Z8m4bjhdaLVMfwV5FCsSTK43wpW8jyMdjq+VO5L6YY6e7W1KPwJGWT+brrCn3lIWie 0fQ7BhbFw63k8KtPfFHN/TFZu/a7KtXYNUySFSUuX0RpniWqfWQipkr41aReMEg2wys+ 247ncNlQOedZcHnqVuA8gx8mW5kvBdYJL2uCja7t+PJKJmFeNkSOWa34yg4pO0FP5ZNl WeGfnUwaUj7H8XHN6FeeTdxWd11UT/fpTcEQKcsZidt2lWQoRH4ciNsj/1g0o14pxz6n 3zS9EPpKYJ4xZHOppJ58pjdvhNdDg1Qu9zVC7dVDrJyPrZ9sd8wAWeMVy7XMFrxG0OYJ bs2Q== X-Gm-Message-State: APjAAAUfQBUM4qg69wObkB3V5pASvpG6ewXuSlK2mfUn0bo91Pk5hU+K gvXqGVlnUpvllMoMIggWTUTc3ndc/iSRgw345IEXqD/U12Q= X-Google-Smtp-Source: APXvYqz3T9ck+K7ecgPhdSVBEcjxN+tZSd/KUHx0fsMq4IqkWsQsPPP9HuYzQzogsOK5ILgLGnnklHXRqJ0pJspXc/s= X-Received: by 2002:ac8:187b:: with SMTP id n56mr630773qtk.173.1581116094258; Fri, 07 Feb 2020 14:54:54 -0800 (PST) MIME-Version: 1.0 From: Ivan Babrou Date: Fri, 7 Feb 2020 14:54:43 -0800 Message-ID: Subject: Reclaim regression after 1c30844d2dfe To: linux-mm@kvack.org Cc: linux-kernel , kernel-team , Andrew Morton , Mel Gorman , Vlastimil Babka Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.006102, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: This change from 5.5 times: * https://github.com/torvalds/linux/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. We can see kswapd quite active in balance_pgdat (it didn't look like it slept at all): $ ps uax | fgrep kswapd root 1850 23.0 0.0 0 0 ? R Jan30 1902:24 [kswapd0] root 1851 1.8 0.0 0 0 ? S Jan30 152:16 [kswapd1] This in turn massively increased pressure on page cache, which did not go well to services that depend on having a quick response from a local cache backed by solid storage. Here's how it looked like when I zeroed vm.watermark_boost_factor: * https://imgur.com/a/6IZWicU IO subsided from 100% busy in page cache population at 300MB/s on a single SATA drive down to under 100MB/s. This sort of regression doesn't seem like a good thing.