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 40F39C3F2D1 for ; Tue, 3 Mar 2020 16:09:23 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id E3D03215A4 for ; Tue, 3 Mar 2020 16:09:22 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E3D03215A4 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 5901F6B0005; Tue, 3 Mar 2020 11:09:22 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 565B96B0006; Tue, 3 Mar 2020 11:09:22 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 47D146B0007; Tue, 3 Mar 2020 11:09:22 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0116.hostedemail.com [216.40.44.116]) by kanga.kvack.org (Postfix) with ESMTP id 32A6F6B0005 for ; Tue, 3 Mar 2020 11:09:22 -0500 (EST) Received: from smtpin17.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 00AC42DEC7 for ; Tue, 3 Mar 2020 16:09:21 +0000 (UTC) X-FDA: 76554535722.17.ring68_497cdc6a1185a Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin17.hostedemail.com (Postfix) with ESMTP id 7A24F18033E75 for ; Tue, 3 Mar 2020 16:05:05 +0000 (UTC) X-HE-Tag: ring68_497cdc6a1185a X-Filterd-Recvd-Size: 2450 Received: from gentwo.org (gentwo.org [3.19.106.255]) by imf06.hostedemail.com (Postfix) with ESMTP for ; Tue, 3 Mar 2020 16:05:04 +0000 (UTC) Received: by gentwo.org (Postfix, from userid 1002) id EACA73F1C0; Tue, 3 Mar 2020 16:05:03 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by gentwo.org (Postfix) with ESMTP id E968E3EECA; Tue, 3 Mar 2020 16:05:03 +0000 (UTC) Date: Tue, 3 Mar 2020 16:05:03 +0000 (UTC) From: Christopher Lameter X-X-Sender: cl@www.lameter.com To: Roman Gushchin cc: Wen Yang , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , Xunlei Pang , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm/slub: improve count_partial() for CONFIG_SLUB_CPU_PARTIAL In-Reply-To: <20200227183519.GA50628@carbon.dhcp.thefacebook.com> Message-ID: References: <20200222092428.99488-1-wenyang@linux.alibaba.com> <20200224165750.GA478187@carbon.dhcp.thefacebook.com> <20200227183519.GA50628@carbon.dhcp.thefacebook.com> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII 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 Thu, 27 Feb 2020, Roman Gushchin wrote: > 1) Reading /proc/slabinfo can cause latency spikes in concurrent memory allocations. > This is the problem which Wen raised initially. Ok. Maybe cache the values or do not read /proc/slabinfo? Use /sys/kernel/slab/... instead? > 2) The number of active objects as displayed in /proc/slabinfo is misleadingly > big if CONFIG_SLUB_CPU_PARTIAL is set. Ok that cou.d be fixed by counting the partial slabs when computing /proc/slabinfo output but that would increase the times even more. > Maybe mixing them in a single workaround wasn't the best idea, but what do you > suggest instead? Read select values from /sys/kernel/slab/.... to determine the values you need and avoid reading those that cause latency spikes. Use the number of slabs for example to estimate the number of objects instead of the number of objects which requires scanning through all the individual slab pages.