[Lancaster] CD Burners

[Richard Robinson]

On Sat, Jul 24, 2004 at 07:32:55PM +0100, Andy Baxter wrote:
> On Saturday 24 July 2004 16:53, Tim Churchill wrote:
> > > You
> >
> > might have to avoid having other stuff thrash the disk / ide bus
> > though,
> > the data has to keep coming fast enough. Possibly more modern ones
> > avoid
> > this, I'm not sure <
> >
> > Practically all IDE burners are 'burn-proof' now, unless you use a
> > second hand one. They need to be set for DMA (can you do that under
> > Linux?) though, as I've seen one fail when it wasn't and too much was
> > asked of it. Even so, I wouldn't recommend trying to do anything much
> > else while burning is in progress unless you have a very fast PC as
> > burning has such a high priority that anything else goes at a crawl.
> >
> 
> that shouldn't matter, i would have thought? I thought that the priority just 
> meant the high priority process gets first chance at any free cycles. but 
> when it's waiting on blocked IO or something, those cycles are available for 
> other processes. 

Yes, I wondered about that. Priorities are a product of the burning
software, not the actual device - and traditionally have been set
high because the burners couldn't afford to miss data when they needed
it. If modern burners can handle this situation better, maybe the
priorities could afford to be turned down ? And still, I'm not sure
that it's a very CPU-intensive process, I _would_ expect the crunch to
be more on the data-movement aspects. Of course, if you really wanted to
be doing lots of other stuff at the same time, you could turn the burn
speed down ?

And, if these things are IDE, I expect you could set DMA in much the same
way as you can for a disk ? Er. <digs into memory> That's in the
IDE-chipset-driver, isn't it ? ISTR having to spot the right chipset option
in a kernel compilation to get it going last time I got a new mobo; and then
it's Just There. Or hdparms, possibly ? Or poke something into
/proc/somethingorother ?

-- 
Richard Robinson
"The whole plan hinged upon the natural curiosity of potatoes" - S. Lem