Date: Tue, 11 Dec 2007 22:10:29 +0100
From: Stefano Brivio <stefano.brivio@polimi.it>
To: Ingo Molnar <mingo@elte.hu>
Cc: Andrew Morton <akpm@linux-foundation.org>, rjw@sisk.pl,
       linux-kernel@vger.kernel.org, torvalds@linux-foundation.org,
       Guillaume Chazarain <guichaz@yahoo.fr>
Subject: Re: 2.6.24-rc4-git5: Reported regressions from 2.6.23
Message-ID: <20071211221029.5af4cb43@morte>
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	<20071210224508.GB27178@elte.hu>
	<20071210230425.GA641@elte.hu>
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	<20071211090120.GA27690@elte.hu>
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On Tue, 11 Dec 2007 10:01:20 +0100
Ingo Molnar <mingo@elte.hu> wrote:

> ok, just to make sure we are all synced up. I made 8 patches related to 
> this problem category (and all the trickle effects). 3 are upstream 
> already, 5 are pending for v2.6.25. One out of those 5 is an immaterial 
> cleanup patch - which leaves us 4 patches to sort out.
> 
> So i'd suggest for you to try latest -git - that will tell us whether 
> udelay() is acceptable on your box right now.

Yes, it is (msleep(2000), as said, gives delays between 2 and 2.9s on my
box, and drivers are happy).

The commit which fixed this (it seems) is
fa2dd441df28b9fdfc68f84ae66f1b507cfff0e4. I'll bisect and tell you more in the
next days.

> i've attached those 4 patches:
> 
>  x86-sched_clock-re-scheduler-fix-x86-regression-in-native-sched-clock.patch
>  x86-cpu-clock-idle-event.patch
>  sched-printk-recursion-fix.patch
>  sched-printk-clock-fix.patch
> 
> none of them is _supposed_ to have any effect on udelay(), but the 
> interactions in this area are weird.

No effects here IIRC.

> [ note: CONFIG_PRINTK_TIME will be broken and only fixed in v2.6.25, so 
>   use some other time metric for determining mdelay quality. ]
> 
> plus then there's this patch:
> 
>   http://lkml.org/lkml/2007/12/7/100
> 
> is it perhaps this one that fixed udelay for you? [ which would be much 
> more expected, as this patch changes udelay ;-) ]

Will try it ASAP, again, in the next few days anyway.


--
Ciao
Stefano
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