Messages in this thread |  | | | Subject | RE: [PATCH] configure HAVE_UNSTABLE_SCHED_CLOCK for SGI_SN systems | | From | Peter Zijlstra <> | | Date | Tue, 06 Jan 2009 21:57:20 +0100 |
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On Tue, 2009-01-06 at 12:34 -0800, Luck, Tony wrote: > > > All ia64 systems are potentially affected ... but perhaps you might > > > never see the problem on most because the itc clocks are synced as close > > > as s/w can get them when cpus are brought on line. > > > > Do you want Dimitri to resubmit with this set for all IA64 or leave it > > as is? > > I'd like to understand the impact of turning on HAVE_UNSTABLE_SCHED_CLOCK > > It looks like both the i386_defconfig and x86_64_defconfig choose this, > so at least ia64 will be hitting the well tested code paths > > Have the other architectures just not hit this yet? Or do they all have > "stable" sched_clock() functions? > > > sched_clock() seemed like such a straightforward thing to begin with. A > quick & easy way to measure a time delta ON THE SAME CPU. I'm not at > all sure why it has been co-opted for general time measurement.
It came from the complication of needing to tell a remote cpu's time due to remote wakeups in the scheduler.
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