Re: dma ripping

[Bill Davidsen]

Daniele Bernardini wrote:
> On Sat, 2004-05-15 at 16:58, Jens Axboe wrote:
>
> > On Sat, May 15 2004, Daniele Bernardini wrote:
> >
> > > On Sat, 2004-05-15 at 12:14, Jens Axboe wrote:
> > >
> > > > On Fri, May 14 2004, Daniele Bernardini wrote:
> > > >
> > > > > Hi Folks, 
> > > > >
> > > > > I am trying to get cd ripping to work on a freshly installed SuSE 9.1 on
> > > > > IBM thinkpad R50 with dvdram drive. 
> > > > >
> > > > > It works for a while and then hangs. At this point nothing short of a
> > > > > reboot works. Ripping stop working when the message 
> > > > > 	cdrom: dropping to single frame dma
> > > > > comes up. The system feels slow for a couple of seconds and then is back
> > > > > to normal, but no ripping until next reboot
> > > > >
> > > > > I am running the 2.6.4 compiled by SuSE.
> > > >
> > > > Can you retest with this small debug patch applied.
> > > >
> > > > --- drivers/cdrom/cdrom.c~	2004-05-15 12:12:24.770228291 +0200
> > > > +++ drivers/cdrom/cdrom.c	2004-05-15 12:13:25.101720866 +0200
> > > > @@ -1987,6 +1987,7 @@
> > > > 			struct request_sense *s = rq->sense;
> > > > 			ret = -EIO;
> > > > 			cdi->last_sense = s->sense_key;
> > > > +			printk("rip failed, sense %x/%x/%x\n", s->sense_key, s->asc, s->ascq);
> > > > 		}
> > > >
> > > > 		if (blk_rq_unmap_user(rq, ubuf, bio, len))
> > >
> > > I did it and started ripping a cd it froze after 9 tracks, though did
> > > not see your message. I was looking at /var/log/messages (see below).
> > > BTW the system got instable and then froze had to power down. It
> > > happened before always after the ripping problem.
> > >
> > > Should I aswitch on debug for the cdrom?
> >
> > Just an idea - can you log vmstat 5 info while doing this burn? Maybe
> > there's still a little leak in there, so watch the ram usage
> > (used/free/swap/cache).
> >
> > Does your drive have dma enabled?
>
>
> dma was off. I turned it on and now everything is fine I am through the
> third cd without a glitch...
>
> Thanks and sorry for being so stupid :)

It seems likely that this kernel was built to enable DMA on disk only, 
an option which is appropriate for a vendor kernel, I guess, but results 
in this behaviour.

In any case it appears that an unexpected feature of PIO mode is now 
behaving in a more useful way, so your report was of general benefit. I 
suspect many people may be unhappy with the CPU used to burn CDs with 
that kernel config, particularly on fast burners.

--
   -bill davidsen (davidsen@xxxxxxx)
"The secret to procrastination is to put things off until the
 last possible moment - but no longer"  -me
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