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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 EF881C4361B for ; Sat, 19 Dec 2020 18:49:12 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 55DD823A00 for ; Sat, 19 Dec 2020 18:49:11 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 55DD823A00 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=zx2c4.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 5FC686B005C; Sat, 19 Dec 2020 13:49:11 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 5ADF76B005D; Sat, 19 Dec 2020 13:49:11 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 4C2CC6B0068; Sat, 19 Dec 2020 13:49:11 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0109.hostedemail.com [216.40.44.109]) by kanga.kvack.org (Postfix) with ESMTP id 35C0B6B005C for ; Sat, 19 Dec 2020 13:49:11 -0500 (EST) Received: from smtpin10.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id E48B34DA9 for ; Sat, 19 Dec 2020 18:49:10 +0000 (UTC) X-FDA: 77610919260.10.week89_4d0865f27448 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin10.hostedemail.com (Postfix) with ESMTP id C583816A4CC for ; Sat, 19 Dec 2020 18:49:10 +0000 (UTC) X-HE-Tag: week89_4d0865f27448 X-Filterd-Recvd-Size: 3036 Received: from mail.zx2c4.com (mail.zx2c4.com [192.95.5.64]) by imf25.hostedemail.com (Postfix) with ESMTP for ; Sat, 19 Dec 2020 18:49:10 +0000 (UTC) Received: by mail.zx2c4.com (ZX2C4 Mail Server) with ESMTP id 0caf822f for ; Sat, 19 Dec 2020 18:41:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=zx2c4.com; h=mime-version :from:date:message-id:subject:to:content-type; s=mail; bh=d3YZzf gl/kfErTfYJBiaP0i2wBM=; b=s6WgYUGVMVP9dslb5X61RaTWYSQzOQyDcwuQPF Lr6RCqVNmBv8hW61jC2MsdK//gVZWmGJlLNxn7PDWpnOXqJAW0MYEGjPrpNpCGwA QK2lITdSWodYWL2Gz6ODBAYw4cjzek79wagGa3+jSDR6jNRvogmNTtcM2JFmMO2z uXcT2o5Q9CzH2Deczyt1/uDZ4T2ZX+f/MnU8ougGYA8CTvqCCntGLjpo7VcZ46ti JGY9TJePt+o2mHI6n8Ar9/bIwwADYx07ZEdGv1swvKZSua4nL1wKtqW094RGEYhX B0KJwBOWT9G3AoVogkFHNot8aUrnvVWCSRRmONP6bWbFDGyw== Received: by mail.zx2c4.com (ZX2C4 Mail Server) with ESMTPSA id f47c80d9 (TLSv1.3:TLS_AES_256_GCM_SHA384:256:NO) for ; Sat, 19 Dec 2020 18:41:06 +0000 (UTC) Received: by mail-yb1-f169.google.com with SMTP id x2so5083068ybt.11 for ; Sat, 19 Dec 2020 10:49:09 -0800 (PST) X-Gm-Message-State: AOAM531IPYj5BHid9BusKi+V4jOEQWQUwCpmB9wApZQgL4tCeMNJcQY1 DL3YNVLe/h/0JMEvtjuQ1XlpCUkFbLj9wyN+/8E= X-Google-Smtp-Source: ABdhPJzFTGDsUJE/0tOWFqalwTo3+PS8i71x6kWlR7RAY2cZJsZyQ/4Ys1UYJiAVD6HeVgpI+NTS4GlRmwu9kjuG6fA= X-Received: by 2002:a5b:78d:: with SMTP id b13mr13256710ybq.123.1608403748689; Sat, 19 Dec 2020 10:49:08 -0800 (PST) MIME-Version: 1.0 From: "Jason A. Donenfeld" Date: Sat, 19 Dec 2020 19:48:58 +0100 X-Gmail-Original-Message-ID: Message-ID: Subject: "tell us why you want to disable CONFIG_COMPACTION" --> spikes from VMs? To: Linux-MM Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000590, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Hi, In trying to debug an issue, I came across this text in the config COMPACTION menu item: > Compaction is the only memory management component to form > high order (larger physically contiguous) memory blocks > reliably. The page allocator relies on compaction heavily and > the lack of the feature can lead to unexpected OOM killer > invocations for high order memory requests. You shouldn't > disable this option unless there really is a strong reason for > it and then we would be really interested to hear about that at > linux-mm@kvack.org. So, here I am as requested. My system has 64 gigs of ram. Often times when starting up VMs, with either QEMU/KVM or with VMware, the VM will be extremely sluggish and laggy for a little while, usually around 5 minutes. During that phase, I see kcompact0 using 100% CPU. But other times this doesn't happen at all. I figured I'd try removing CONFIG_COMPACTION and seeing what happens, but then I saw your admonishment, so here I am. Has anybody else seen this behavior? Jason