Re: [PATCH 13/15] sched: Use a static_key for sched_clock_stable

[Markus Trippelsdorf <markus@trippelsdorf.de>]

On 2014.01.22 at 13:07 +0100, Peter Zijlstra wrote:
> On Wed, Jan 22, 2014 at 01:00:48PM +0100, Markus Trippelsdorf wrote:
> > FYI it happens on real hardware on my machine:
> > ...
> > [    0.000000] Hierarchical RCU implementation.
> > [    0.000000] NR_IRQS:4352 nr_irqs:712 16
> > [    0.000000] spurious 8259A interrupt: IRQ7.
> > [    0.000000] Console: colour VGA+ 80x25
> > [    0.000000] console [tty0] enabled
> > [    0.000000] hpet clockevent registered
> > [    0.000000] tsc: Fast TSC calibration using PIT
> > [    0.003333] tsc: Detected 3210.681 MHz processor
> > [   60.375238] Calibrating delay loop (skipped), value calculated using timer frequency.. 6423.91 BogoMIPS (lpj=10702270)
> > [   60.375240] pid_max: default: 32768 minimum: 301
> > [   60.375259] Mount-cache hash table entries: 256
> > [   60.375373] tseg: 0000000000
> > [   60.375377] CPU: Physical Processor ID: 0
> > [   60.375377] CPU: Processor Core ID: 0
> > [   60.375378] mce: CPU supports 6 MCE banks
> > [   60.375382] LVT offset 0 assigned for vector 0xf9
> > [   60.375384] process: using AMD E400 aware idle routine
> > [   60.375386] Last level iTLB entries: 4KB 512, 2MB 16, 4MB 8
> 
> Should have always happened like that I think. From the log it looks
> like the moment we switch from jiffies to actual TSC in
> arch/x86/kernel/tsc.c:sched_clock().
> 
> I don't think I changed the logic there, just switched from a condition
> to a jump_label.

Well, v3.13 was fine. So it's definitely a regression. But it may be
another issue. I will try to bisect later.

-- 
Markus