Messages in this thread | | | Date | Fri, 10 Oct 2008 11:17:11 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH] sched_clock: prevent scd->clock from moving backwards |
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* Dave Kleikamp <shaggy@linux.vnet.ibm.com> wrote:
> On Thu, 2008-10-09 at 12:54 -0500, Dave Kleikamp wrote: > > > I'll fix the patch and retest it before sending it again. > > I'm definitely running with the new patch now. Here goes: > ------------------------------------------------- > sched_clock: prevent scd->clock from moving backwards > > When sched_clock_cpu() couples the clocks between two cpus, it may > increment scd->clock beyond the GTOD tick window that __update_sched_clock() > uses to clamp the clock. A later call to __update_sched_clock() may move > the clock back to scd->tick_gtod + TICK_NSEC, violating the clock's > monotonic property. > > This patch ensures that scd->clock will not be set backward. > > Signed-off-by: Dave Kleikamp <shaggy@linux.vnet.ibm.com> > Cc: Ingo Molnar <mingo@elte.hu> > Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
applied to tip/sched/clock, thanks Dave!
Ingo
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