linux-kernel - Re: Burning multiple DVDs at one time

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Message-ID: <20120318150127.5f8db40c@stein>
Date:	Sun, 18 Mar 2012 15:01:27 +0100
From:	Stefan Richter <stefanr@...6.in-berlin.de>
To:	Wakko Warner <wakko@...mx.eu.org>
Cc:	linux-kernel@...r.kernel.org, linux-scsi@...r.kernel.org
Subject: Re: Burning multiple DVDs at one time

On Mar 18 Wakko Warner wrote:
> Stefan Richter wrote:
> > On Mar 17 Wakko Warner wrote:
> > > Thanks.  I looked at the patch.  I would just like to confirm that I can
> > > patch my 3.0.0 vanilla kernel, compile the sr module, unload the current and
> > > load the patched one without the need to reboot.
> > 
> > Yes, this should be possible.
> > 
> > Oh, I only noticed just know that you also wrote:
> > 
> > > > > The kernel is a vanilla kernel v3.0.0.  (This also happened with 2.6.35)
> > 
> > In 2.6.35, the Big Kernel Lock was still in place there.  That lock
> > behaved differently from a plain mutex --- notably it was released when a
> > thread went to sleep --- so maybe there is more to your problem than just
> > sr_mutex blocking unrelated sr accesses.
> 
> There is a good possibility that I was mistaken on the 2.6.35.
> 
> I manually applied your patch to 3.0.0, compiled, removed sr-mod module and
> inserted the newly compiled one.
> 
> With the vanilla one, I would see the buf % in wodim drop while the fifo was
> full.  With the patch (removing the mutex), buf stayed above 98% and the
> burn speed was 16x at the end (10x avg).
> 
> Seems to have fixed my problem.

Very nice; so there is an almost easy fix.  Now I or somebody else need to
work out the required cdrom_device_info protection on which Arnd and James
commented.
-- 
Stefan Richter
-=====-===-- --== =--=-
http://arcgraph.de/sr/
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