Date: Sat, 19 Mar 2005 08:56:30 -0700 From: Scott Long <scottl@samsco.org> To: Danny Braniss <danny@cs.huji.ac.il> Cc: net@freebsd.org Subject: Re: iSCSI initiator driver beta version, testers wanted Message-ID: <423C4BAE.3010202@samsco.org> In-Reply-To: <423C4037.3090801@samsco.org> References: <E1DCcbo-000ABI-Fu@cs1.cs.huji.ac.il> <423C4037.3090801@samsco.org>
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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. > > 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
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