Date: Thu, 28 Sep 2006 00:54:23 +0100 From: "Steven Hartland" <killing@multiplay.co.uk> To: "Scott Long" <scottl@samsco.org>, "David G Lawrence" <dg@dglawrence.com> Cc: Peter Jeremy <peterjeremy@optushome.com.au>, freebsd-stable@freebsd.org, Oliver Brandmueller <ob@e-Gitt.NET>, John Baldwin <jhb@freebsd.org> Subject: Re: 6.2 SHOWSTOPPER - em completely unusable on 6.2 Message-ID: <002201c6e290$45ece980$b3db87d4@multiplay.co.uk> References: <451A1375.5080202@gneto.com> <20060927071538.GF22229@e-Gitt.NET><451A4189.5020906@samsco.org> <20060927152824.GJ22229@e-Gitt.NET><20060927155553.GB14563@icarus.home.lan><20060927155904.GM22229@e-Gitt.NET> <451AA7B1.5080202@samsco.org><20060927191402.GB932@turion.vk2pj.dyndns.org><20060927210349.GG14975@tnn.dglawrence.com> <451AEB02.2090806@samsco.org>
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Scott Long wrote: > Well, I kinda danced around the issue before, but I'll say it now. I, > as well as a few others, have seen instances of Giant being held by > the syncer for 5 or more seconds at a time. I can't explain why, and > I've never been able to catch it in the act in a meaningful way. But > it is known to happen. My best wild guess is that the syncer is > doing a lot of work (there is no question here), and keeps on getting > preempted, and as part of this, it blocks without locks being > dropped. Actually, this is most likely exactly what is going on. > The syncer is sending out I/O and is getting interrupted+preempted by > the sata controller+driver, and it winds up making very slow > progress, while never actually releasing Giant. This could explain behaviour we've seen on busy boxes here. You'll be typing away doing something and then bang everything stalls. A few seconds later everything continues what may be interesting about this is that its on 5.4-RELEASE as well as 6.1-RELEASE. ================================================ This e.mail is private and confidential between Multiplay (UK) Ltd. and the person or entity to whom it is addressed. In the event of misdirection, the recipient is prohibited from using, copying, printing or otherwise disseminating it or any information contained in it. In the event of misdirection, illegible or incomplete transmission please telephone +44 845 868 1337 or return the E.mail to postmaster@multiplay.co.uk.
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