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Date:      Thu, 11 Feb 1999 03:16:37 +0100
From:      Bjoern Fischer <bfischer@Techfak.Uni-Bielefeld.DE>
To:        Matthew Dillon <dillon@apollo.backplane.com>
Cc:        Bjoern Fischer <bfischer@Techfak.Uni-Bielefeld.DE>, freebsd-stable@FreeBSD.ORG
Subject:   Re: NFS + cdda2wav
Message-ID:  <19990211031636.A2690@broccoli.no-support.loc>
In-Reply-To: <199902100355.TAA77997@apollo.backplane.com>; from Matthew Dillon on Tue, Feb 09, 1999 at 07:55:20PM -0800
References:  <19990209233951.A402@broccoli.no-support.loc> <199902100355.TAA77997@apollo.backplane.com>

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On Tue, Feb 09, 1999 at 07:55:20PM -0800, Matthew Dillon wrote:
[...]
>      Bjoern, ktrace the program run.  I suspect the problem is not
>      NFS but that the write() latency is causing one of cdda2wav's
>      forked processes to exit and kill its child before the child
>      finishes writing.
> 
>      ktrace -t cn -i cdda2wav ....
> 
>      kdump -R | less
> 
>      Try to match up reads from the CD to writes to the output file.
>      See if the final couple of read/write's match up.

Hmm, the procedure of testing changes the object being tested.
The problem disappears while ktracing the run.

In the kdump I could see that the size of the last write to the
audio file is exactly what is missing without ktrace. The last
write is simply skipped.

Then I compiled the whole thing for debugging. Synchronization
between the parent (writing) process and the child (reading)
process is managed with fifos. Just before the last write should
be done the syncing function receives a SIGPIPE as it was trying
to write to the pipe. At the time I don't know how this can happen.

  Bjoern

-- 
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------END GEEK CODE BLOCK------

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