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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6ECA2C433EF for ; Thu, 2 Jun 2022 15:14:45 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id EC02B6B0071; Thu, 2 Jun 2022 11:14:44 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id E716E6B0073; Thu, 2 Jun 2022 11:14:44 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D82936B0074; Thu, 2 Jun 2022 11:14:44 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id C92616B0071 for ; Thu, 2 Jun 2022 11:14:44 -0400 (EDT) Received: from smtpin13.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay13.hostedemail.com (Postfix) with ESMTP id 8C84760AB9 for ; Thu, 2 Jun 2022 15:14:44 +0000 (UTC) X-FDA: 79533642888.13.B176628 Received: from gentwo.de (gentwo.de [161.97.139.209]) by imf15.hostedemail.com (Postfix) with ESMTP id 1C58FA0051 for ; Thu, 2 Jun 2022 15:14:19 +0000 (UTC) Received: by gentwo.de (Postfix, from userid 1001) id E7CB4B00142; Thu, 2 Jun 2022 17:14:41 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gentwo.de; s=default; t=1654182881; bh=hvAa6ofYWFV4vL+MuhdmzPAGvRtWimk/1jDhChMw+d0=; h=Date:From:To:cc:Subject:In-Reply-To:References:From; b=JZykwXFzjruFfTKkX3UXi5/LSC3/9+ffdOnwVbFsJ5PT+5Rma/6SAwgxKYF253WD/ o4GQZBvAK2C2YH8NCmGUWCb0LHCVVeAIIulr9Ok0cx7UKLeL3GfWf+j4KLvlRATjzX pJJMnP/PLp3qFQdduh1gPI1o+52T8rkhnQY+E1p4K7ixZiIhATFOhxxXQQMbsIYV/G JfCCIDTJXyxTYbcnVY3Tgj2NRbIFb+lzsEaDvcUaOR26sdoyoOhLMx8n7qRav+mror Nlm2lKYYjDzmGU+cyP0kIEnGS7xg323pzbsZRtQ/XAVWTpqnuSl52LrdNT0Iq764WB j3n8cekSReFhw== Received: from localhost (localhost [127.0.0.1]) by gentwo.de (Postfix) with ESMTP id E6966B0013B; Thu, 2 Jun 2022 17:14:41 +0200 (CEST) Date: Thu, 2 Jun 2022 17:14:41 +0200 (CEST) From: Christoph Lameter To: David Rientjes cc: Hyeonggon Yoo <42.hyeyoo@gmail.com>, Rongwei Wang , akpm@linux-foundation.org, vbabka@suse.cz, roman.gushchin@linux.dev, iamjoonsoo.kim@lge.com, penberg@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/3] mm/slub: fix the race between validate_slab and slab_free In-Reply-To: Message-ID: References: <20220529081535.69275-1-rongwei.wang@linux.alibaba.com> User-Agent: Alpine 2.22 (DEB 394 2020-01-19) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 1C58FA0051 X-Stat-Signature: zq7w4hntfkznkfxkaqq1bmiairkc9pxr X-Rspam-User: Authentication-Results: imf15.hostedemail.com; dkim=pass header.d=gentwo.de header.s=default header.b=JZykwXFz; spf=pass (imf15.hostedemail.com: domain of cl@gentwo.de designates 161.97.139.209 as permitted sender) smtp.mailfrom=cl@gentwo.de; dmarc=pass (policy=none) header.from=gentwo.de X-HE-Tag: 1654182859-700276 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 Mon, 30 May 2022, David Rientjes wrote: > > Unconditionally taking n->list_lock will degrade performance. > > This is a good point, it would be useful to gather some benchmarks for > workloads that are known to thrash some caches and would hit this path > such as netperf TCP_RR. Its obvious that adding new spinlocks to some of the hottest functions in the kernel will degrade performance. This goes against the basic design of these functions to be as efficient as possible.