Date: Sat, 19 Mar 2005 20:06:20 +0200 From: Danny Braniss <danny@cs.huji.ac.il> To: Scott Long <scottl@samsco.org> Cc: net@freebsd.org Subject: Re: iSCSI initiator driver beta version, testers wanted Message-ID: <E1DCiL6-000MUy-6n@cs1.cs.huji.ac.il> In-Reply-To: Your message of Sat, 19 Mar 2005 08:56:30 -0700 .
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> Scott Long wrote: > > Danny Braniss wrote: > > > >>> with tags enabled, iSCSI is much faster, but it also causes a > >>> deadlock :-( > >>> this is what i run: > >>> newfs -U /<iscsi device> > >>> cd /<iscsi device> > >>> restore rf /home/file.dump > >>> > >>> on the same motherboard, a dual Xeon, with smp disabled all is OK > >>> with smp enabled restore gets stuck usualy waiting on biord. > >>> the iscsi driver shows that all requests have been done, the sniffing > >>> shows the same(ie all request have been done). > >>> > >>> so this leads me to think that there is some race condition that i'm not > >>> aware of in a SMP system, where xpt_done(ccb) is called while > >>> another process is calling biowait. > >>> > >>> another lead is that after restore gets stuck, the system slowly gets > >>> 'stalled'. > >>> > >>> any insight is most welcome!, i'm also stuck. > >> > >> > >> > >> ahh, hate talking to myself :-) > >> > >> grabbing Giant before calling xpt_done solved it, so the problem is > >> most probably in the CAM ... > >> > >> danny > >> > >> > >> > > > > No, you need to grab Giant when calling xpt_done(). I even put an > > assertion into CAM to make sure of that. Are you running with WITNESS > > and/or INVARIANTS enabled? Those would have caught this problem. > > they are off :-(, would have saved me some time. > > Scott > > Oops, I forgot to mention that I recently addressed this in 6-CURRENT. > Now, much of the rest of cam API still requires Giant to be held, but > xpt_done() does not. This only applies to 6-CURRENT, and I doubt that > it will be backported to 5-STABLE. > > Scott so what you are saying is that in 5.x it's a must to grab Giant before calling xpt_done, and not in 6? danny
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