On Saturday, 25 of October 2008, David Miller wrote:

From: "Rafael J. Wysocki" <redacted>
Date: Sat, 25 Oct 2008 00:25:34 +0200

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On Friday, 10 of October 2008, Ingo Molnar wrote:

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* Evgeniy Polyakov [off-list ref] wrote:

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On Fri, Oct 10, 2008 at 01:42:45PM +0200, Ingo Molnar (mingo@elte.hu) wrote:

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vanilla 27: 347.222
no TSO/GSO: 357.331
no hrticks: 382.983
no balance: 389.802

okay. The target is 470 MB/sec, right? (Assuming the workload is sane 
and 'fixing' it does not mean we have to schedule worse.)

Well, that's where I started/stopped, so maybe we will even move
further? :)

that's the right attitude ;)

Can anyone please tell me if there was any conclusion of this thread?

I made some more analysis in private with Ingo and Peter Z. and found
that the tbench decreases correlate pretty much directly with the
ongoing increasing cpu cost of wake_up() and friends in the fair
scheduler.

The largest increase in computational cost of wakeups came in 2.6.27
when the hrtimer bits got added, it more than tripled the cost of a wakeup.
In 2.6.28-rc1 the hrtimer feature has been disabled, but I think that
should be backports into the 2.6.27-stable branch.

Thanks a lot for the info.

Could you please give me a pointer to the commit disabling the hrtimer feature?

Rafael