Re: [patch] fix the softlockup watchdog to actually work

[Ingo Molnar <mingo@elte.hu>]

* Jeremy Fitzhardinge <jeremy@goop.org> wrote:

> Ingo Molnar wrote:
> > no, the return value after idling can be completely random on some 
> > boxes, on a 64-bit scale - triggering the softlockup watchdog randomly. 
> > (some boxes return random TSC values, etc.) Again, it's fine for the 
> > scheduler's purpose, that's why i named it sched_clock().
> >
> > the proper clocksource use within the kernel is ktime_get() [or 
> > ktime_get_ts()]. Do not abuse sched_clock() for such things.
> 
> Well, my observation is that both softlockup and the scheduler really 
> want to measure unstolen time, so it seemed to me that sched_clock was 
> a nice common place to implement that, rather than implementing a 
> whole new time interface.  At the time that seemed OK, and nobody had 
> any objections.

yeah. But then it should not be using sched_clock() but CFS's new 
rq_clock() method - which does try to construct a globally valid 
timesource out of sched_clock(). [that fix is not backportable though]

	Ingo