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

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Date:	Sun, 18 Mar 2012 09:30:59 -0400
From:	Wakko Warner <wakko@...mx.eu.org>
To:	Stefan Richter <stefanr@...6.in-berlin.de>
Cc:	linux-kernel@...r.kernel.org, linux-scsi@...r.kernel.org
Subject: Re: Burning multiple DVDs at one time

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.

Thanks.

-- 
 Microsoft has beaten Volkswagen's world record.  Volkswagen only created 22
 million bugs.
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