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

Hi,

On Wednesday 20 June 2007, Thanos Kyritsis wrote:

On Monday 18 June 2007, Mark Lord wrote:

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Thanos Kyritsis wrote:

[snip]

quoted

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/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]

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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...

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????

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