Re: [PROBLEM]: hdparm strange behaviour for 2.6.21 and later

[Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>]

Hi,

On Wednesday 20 June 2007, Thanos Kyritsis wrote:
> On Monday 18 June 2007, Mark Lord wrote:
> > Thanos Kyritsis wrote:
> [snip]
> > > /etc/rc.d/rc.local contains the following:
> > > /usr/sbin/hdparm -q -d1 -q -u1 -q -c1 -q -k1 /dev/hda
> > > /usr/sbin/hdparm -q -d1 -q -u1 -q -c1 -q -k1 /dev/hdb
> [snip]
> 
> > Sounds like a (kernel) timing issue.
> > The "-q" option gets rid of some intermediary printf's,
> > and nothing else.  So with -q, the ioctl() calls happen
> > much closer together in time.  Without -q, the intermediary
> > printf's likely cause a resched, giving the kernel more time
> > to complete anything left over from the earlier call.

It could be that some assumptions that I've taken when
fixing DMA tuning locking were wrong...

> > ????
> >
> > Any difference with a modern version of hdparm?
> 
> The same issue happens when using hdparm 7.4 as well as 7.5.

Adding a couple of printk-s to ide.c::set_using_dma() and
ide.c::ide_spin_wait_hwgroup() will for sure help in debugging
it further.

Also could you try running UP kernel without PREEMPT and see
if it makes difference?

Thanks,
Bart