Re: iSCSI initiator driver beta version, testers wanted

From: Scott Long (scottl_at_samsco.org)
Date: 03/19/05

  • Next message: Scott Long: "Re: iSCSI initiator driver beta version, testers wanted" 
    Date: Sat, 19 Mar 2005 08:07:35 -0700
To: Danny Braniss <danny@cs.huji.ac.il>

    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
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