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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,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 35FBBC433E0 for ; Mon, 22 Mar 2021 10:23:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F16576198C for ; Mon, 22 Mar 2021 10:23:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229994AbhCVKW5 (ORCPT ); Mon, 22 Mar 2021 06:22:57 -0400 Received: from mx2.suse.de ([195.135.220.15]:47364 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229508AbhCVKWp (ORCPT ); Mon, 22 Mar 2021 06:22:45 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 9B37DAD71; Mon, 22 Mar 2021 10:22:44 +0000 (UTC) Subject: Re: [PATCH v4 1/3] mm/slub: Introduce two counters for partial objects To: Shu Ming , Xunlei Pang Cc: Christoph Lameter , Christoph Lameter , Pekka Enberg , Roman Gushchin , Konstantin Khlebnikov , David Rientjes , Matthew Wilcox , Andrew Morton , LKML , linux-mm@kvack.org, Wen Yang , James Wang References: <1615967692-80524-1-git-send-email-xlpang@linux.alibaba.com> <1615967692-80524-2-git-send-email-xlpang@linux.alibaba.com> <42b5dba7-f89f-ae43-3b93-f6e4868e1573@suse.cz> <34a07677-3afe-465c-933e-dc9503e9634d@linux.alibaba.com> From: Vlastimil Babka Message-ID: <2ad0539f-2c38-714e-330e-7709bb07ebac@suse.cz> Date: Mon, 22 Mar 2021 11:22:43 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 3/22/21 2:46 AM, Shu Ming wrote: > More precisely, ss will count partial objects like denty objects with > "/sys/kernel/slab/dentry/partial" whose number can become huge. Uh, that's interesting. Would you know what exactly it uses the value for? I can think of several reasons why it might be misleading. > On Thu, Mar 18, 2021 at 8:56 PM Xunlei Pang wrote: >> >> >> >> On 3/18/21 8:18 PM, Vlastimil Babka wrote: >> > On 3/17/21 8:54 AM, Xunlei Pang wrote: >> >> The node list_lock in count_partial() spends long time iterating >> >> in case of large amount of partial page lists, which can cause >> >> thunder herd effect to the list_lock contention. >> >> >> >> We have HSF RT(High-speed Service Framework Response-Time) monitors, >> >> the RT figures fluctuated randomly, then we deployed a tool detecting >> >> "irq off" and "preempt off" to dump the culprit's calltrace, capturing >> >> the list_lock cost nearly 100ms with irq off issued by "ss", this also >> >> caused network timeouts. >> > >> > I forgot to ask, how does "ss" come into this? It displays network connections >> > AFAIK. Does it read any SLUB counters or slabinfo? >> > >> >> ss may access /proc/slabinfo to acquire network related slab statistics. >