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=-0.8 required=3.0 tests=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 CD561C3F2CE for ; Wed, 4 Mar 2020 16:21:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9E4C1215A4 for ; Wed, 4 Mar 2020 16:21:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388242AbgCDQVO (ORCPT ); Wed, 4 Mar 2020 11:21:14 -0500 Received: from zeniv.linux.org.uk ([195.92.253.2]:59402 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388215AbgCDQVO (ORCPT ); Wed, 4 Mar 2020 11:21:14 -0500 Received: from viro by ZenIV.linux.org.uk with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1j9WlP-005GmR-La; Wed, 04 Mar 2020 16:20:51 +0000 Date: Wed, 4 Mar 2020 16:20:51 +0000 From: Al Viro To: Matthew Wilcox Cc: "Eric W. Biederman" , Linus Torvalds , linux-fsdevel , Linux Kernel Mailing List Subject: Re: [RFC][PATCHSET] sanitized pathwalk machinery (v3) Message-ID: <20200304162051.GQ23230@ZenIV.linux.org.uk> References: <20200223011154.GY23230@ZenIV.linux.org.uk> <20200301215125.GA873525@ZenIV.linux.org.uk> <20200302003926.GM23230@ZenIV.linux.org.uk> <87o8tdgfu8.fsf@x220.int.ebiederm.org> <20200304002434.GO23230@ZenIV.linux.org.uk> <87wo80g0bo.fsf@x220.int.ebiederm.org> <20200304065547.GP23230@ZenIV.linux.org.uk> <20200304132812.GE29971@bombadil.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200304132812.GE29971@bombadil.infradead.org> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Mar 04, 2020 at 05:28:12AM -0800, Matthew Wilcox wrote: > On Wed, Mar 04, 2020 at 06:55:47AM +0000, Al Viro wrote: > > On Tue, Mar 03, 2020 at 11:23:39PM -0600, Eric W. Biederman wrote: > > > Do the xfs-tests cover that sort of thing? > > > The emphasis is stress testing the filesystem not the VFS but there is a > > > lot of overlap between the two. > > > > I do run xfstests. But "runs in KVM without visible slowdowns" != "won't > > cause them on 48-core bare metal". And this area (especially when it > > comes to RCU mode) can be, er, interesting in that respect. > > > > FWIW, I'm putting together some litmus tests for pathwalk semantics - > > one of the things I'd like to discuss at LSF; quite a few codepaths > > are simply not touched by anything in xfstests. > > Might be more appropriate for LTP than xfstests? will-it-scale might be > the right place for performance benchmarks. Might be... I do run LTP as well, but it's still a 4-way KVM on a 6-way amd64 host (phenom II X6 1100T) - not well-suited for catching scalability issues. Litmus tests mentioned above are more about verifying the semantics; I hadn't moved past the "bunch of home-grown scripts creating setups that would exercise the codepaths in question + trivial pieces in C, pretty much limited to syscall()" stage with that; moving those to LTP framework is something I'll need to look into. Might very well make sense; for now I just want a way to get test coverage of that code with minimal headache.