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Date:      Tue, 27 Oct 2009 08:04:45 +1100
From:      Andrew Reilly <areilly@bigpond.net.au>
To:        "b. f." <bf1783@googlemail.com>
Cc:        freebsd-stable@FreeBSD.org
Subject:   Re: Some questions about da0 on USB2 (recent bad behaviour)
Message-ID:  <20091026210445.GA66088@duncan.reilly.home>
In-Reply-To: <d873d5be0910241207o2ae4be8ah6db9a7996581ec69@mail.gmail.com>
References:  <d873d5be0910241207o2ae4be8ah6db9a7996581ec69@mail.gmail.com>

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On Sat, Oct 24, 2009 at 07:07:00PM +0000, b. f. wrote:
> >That is: it seems to work fine for some fraction of a minute
> >(doesn't seem to be longer than a minute, anyway), and then
> >stops completely for several minutes (processes reading or
> >writing sit in "D" state in ps) and then starts again, after
> >logging "Request completed with CAM_REQ_CMP_ERR\nRetrying
> >Command".
> 
> In the past week or so, Alexander Motin (mav@FreeBSD.org) and Andrew
> Thompson (thompsa@FreeBSD.org) have made a number of related changes
> to cam and usb in the P4 repository, and in 9-CURRENT.  Some of these
> may address your problem.  I'm not sure when they will be back-ported
> to 8.X.  You may wish to try out the latest version of -CURRENT, to
> see if it solves your problem(s); or to contact them.

I've done this, and it seems to have worked.  It seems possible
that the bulk throughput (measured by systat while doing a cat
/backup/bigfile >/dev/null) might even have increased a bit,
but maybe not.  The big improvement is that the transfer isn't
pausing any more.  No more CAM_REQ_CMP_ERR messages.

Thanks b. f. for the suggestion, and thanks Alexander and Andrew
for the fixes!

I haven't run -current for, probably, ten years, and the
occasional messages about lock-order-reversals worry me a bit,
but don't seem to be doing any harm.  Should I report them?  In
a PR?

Please count this message as a vote for MFC'ing those cam and
usb changes to 8-STABLE.

Cheers,

-- 
Andrew



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