Re: Regression in 2.6.27 caused by commit bfc0f59

From: Larry Finger
Date: Mon Sep 01 2008 - 16:23:20 EST


Thomas Gleixner wrote:
On Mon, 1 Sep 2008, Larry Finger wrote:
The timed sleep is as accurate as I can measure.

I put in some test prints. The value of pm2 is zero when the else branch of
the "if (hpet)" is entered; however, pm1 is 15768471. When we reach the
do_div(tsc2, tsc1) statement, tsc2 is zero, which I think means that the two
calls to tsc_read_refs() are returning the same junk value.

Ok, so the pmtimer is probably detected later as unusable and disabled.
Please check your logs for: "PM-Timer had inconsistent results:"

Booting 2.6.26, the dmesg output has a line that says:

PM-Timer running at invalid rate: 200% of normal - aborting.

Amazing that it should be exactly 200%. Why is the CPU running at half speed when the PM-Timer rate is measured?

Larry
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