From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg Freemyer Subject: Re: Date: Sun, 5 Apr 2009 07:42:18 -0400 Message-ID: <87f94c370904050442h7bcd0f8fp6d32d942372f7e93@mail.gmail.com> References: <87f94c370904041738g4ef6221co6c3ace1ebf51dcdf@mail.gmail.com> <20090405050520.KWXV19140.cdptpa-omta03.mail.rr.com@Leslie> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <20090405050520.KWXV19140.cdptpa-omta03.mail.rr.com@Leslie> Sender: linux-raid-owner@vger.kernel.org To: lrhorer@satx.rr.com Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids On Sun, Apr 5, 2009 at 1:05 AM, Lelsie Rhorer wro= te: >> Alternate theory - serious fsync performance issue >> >> I don't know if it's related, but there is a lot of recent discussio= n >> related to fsync causing large delays in ext3. =A0Linus is saying hi= s >> highspeed SDD is seeing multisecond delays. =A0He is very frustrated >> because the SDD should be more or less instantaneous. >> >> The current thread is http://markmail.org/message/adiyz3lri6tlueaf >> >> In one of the other threads I saw someone saying that in one test th= ey >> had a fsync() call take minutes to return. =A0Apparently no one yet >> fully understands what is going on. =A0Seems like something that cou= ld >> in some way be related to what you are seeing. > > Well, it could be. =A0I tried flushing the cashes numerous times whil= e > testing, but I never could see it made a difference one way or the ot= her. > In a separate thread you said it was reiser and what I have seen discussed is ext3, so you may be safe from that bug. As to flushing caches, I don't think that is the same thing. This bug specifically impacts fsyncs on a small file while a heavy i/o load is underway via other processes. The elevators were being discussed as part of the problem and fsync triggers different elevator logic than sync or drop_caches does. Greg --=20 Greg Freemyer Head of EDD Tape Extraction and Processing team Litigation Triage Solutions Specialist http://www.linkedin.com/in/gregfreemyer =46irst 99 Days Litigation White Paper - http://www.norcrossgroup.com/forms/whitepapers/99%20Days%20whitepaper.p= df The Norcross Group The Intersection of Evidence & Technology http://www.norcrossgroup.com -- To unsubscribe from this list: send the line "unsubscribe linux-raid" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html