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=-2.2 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 7012DC352A3 for ; Fri, 14 Feb 2020 02:16:33 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 449792082F for ; Fri, 14 Feb 2020 02:16:33 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 449792082F 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 E5ABA6B05D4; Thu, 13 Feb 2020 21:16:32 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id DE37C6B05D5; Thu, 13 Feb 2020 21:16:32 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id CF8E06B05D6; Thu, 13 Feb 2020 21:16:32 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0083.hostedemail.com [216.40.44.83]) by kanga.kvack.org (Postfix) with ESMTP id B4F426B05D4 for ; Thu, 13 Feb 2020 21:16:32 -0500 (EST) Received: from smtpin13.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 6D8C2180AD81A for ; Fri, 14 Feb 2020 02:16:32 +0000 (UTC) X-FDA: 76487118624.13.suit81_562b00f840d19 X-HE-Tag: suit81_562b00f840d19 X-Filterd-Recvd-Size: 1956 Received: from gentwo.org (gentwo.org [3.19.106.255]) by imf23.hostedemail.com (Postfix) with ESMTP for ; Fri, 14 Feb 2020 02:16:32 +0000 (UTC) Received: by gentwo.org (Postfix, from userid 1002) id 94F033EC23; Fri, 14 Feb 2020 02:16:31 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by gentwo.org (Postfix) with ESMTP id 942983E871; Fri, 14 Feb 2020 02:16:31 +0000 (UTC) Date: Fri, 14 Feb 2020 02:16:31 +0000 (UTC) From: Christopher Lameter X-X-Sender: cl@www.lameter.com To: Andrew Morton cc: Wen Yang , Pekka Enberg , David Rientjes , Joonsoo Kim , Xunlei Pang , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm/slub: Detach node lock from counting free objects In-Reply-To: <20200212145615.3518e29ec90d580817c14dc8@linux-foundation.org> Message-ID: References: <20200201031502.92218-1-wenyang@linux.alibaba.com> <5373ce28-c369-4e40-11dd-b269e4d2cb24@linux.alibaba.com> <20200212145615.3518e29ec90d580817c14dc8@linux-foundation.org> 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 Wed, 12 Feb 2020, Andrew Morton wrote: > : reading "/proc/slabinfo" can possibly block the slab allocation on > : another CPU for a while, 200ms in extreme cases > > That was bad of us. It would be good to stop doing this. The count is not needed for any operations. Just for the slabinfo output. The value has no operational value for the allocator itself. So why use extra logic to track it in potentially performance critical paths? One could estimate the number of objects from the number of allocated slabs instead?