From mboxrd@z Thu Jan 1 00:00:00 1970 From: Howard Chu Subject: Re: xfs: does mkfs.xfs require fancy switches to get decent performance? (was Tux3 Report: How fast can we fsync?) Date: Tue, 12 May 2015 14:26:07 +0100 Message-ID: <5551FF6F.8060000@symas.com> References: <1430395641.3180.94.camel@gmail.com> <1430401693.3180.131.camel@gmail.com> <55423732.2070509@phunq.net> <55423C05.1000506@symas.com> <554246D7.40105@phunq.net> <20150511221223.GD4434@amd> <20150511231714.GD14088@thunk.org> <555166BA.1050606@phunq.net> <20150512090300.GA15574@amd> <5551E269.3040208@phunq.net> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Cc: Theodore Ts'o , Mike Galbraith , Dave Chinner , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, tux3@tux3.org, OGAWA Hirofumi To: Daniel Phillips , Pavel Machek Return-path: In-Reply-To: <5551E269.3040208@phunq.net> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org Daniel Phillips wrote: > On 05/12/2015 02:03 AM, Pavel Machek wrote: >> I'd call system with 65 tasks doing heavy fsync load at the some time >> "embarrassingly misconfigured" :-). It is nice if your filesystem can >> stay fast in that case, but... > > Well, Tux3 wins the fsync race now whether it is 1 task, 64 tasks or > 10,000 tasks. At the high end, maybe it is just a curiosity, or maybe > it tells us something about how Tux3 is will scale on the big machines > that XFS currently lays claim to. And Java programmers are busy doing > all kinds of wild and crazy things with lots of tasks. Java almost > makes them do it. If they need their data durable then they can easily > create loads like my test case. > > Suppose you have a web server meant to serve 10,000 transactions > simultaneously and it needs to survive crashes without losing client > state. How will you do it? You could install an expensive, finicky > database, or you could write some Java code that happens to work well > because Linux has a scheduler and a filesystem that can handle it. > Oh wait, we don't have the second one yet, but maybe we soon will. > > I will not claim that stupidly fast and scalable fsync is the main > reason that somebody should want Tux3, however, the lack of a high > performance fsync was in fact used as a means of spreading FUD about > Tux3, so I had some fun going way beyond the call of duty to answer > that. By the way, I am still waiting for the original source of the > FUD to concede the point politely, but maybe he is waiting for the > code to land, which it still has not as of today, so I guess that is > fair. Note that it would have landed quite some time ago if Tux3 was > already merged. Well, stupidly fast and scalable fsync sounds wonderful to me; it's the primary pain point in LMDB write performance now. http://symas.com/mdb/ondisk/ I look forward to testing Tux3 when usable code shows up in a public repo. -- -- Howard Chu CTO, Symas Corp. http://www.symas.com Director, Highland Sun http://highlandsun.com/hyc/ Chief Architect, OpenLDAP http://www.openldap.org/project/