Messages in this thread | | | Date | Wed, 15 Feb 2012 15:16:34 +0100 (CET) | From | Thomas Gleixner <> | Subject | Re: [PATCH] specific do_timer_cpu value for nohz off mode |
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On Tue, 8 Nov 2011, Dimitri Sivanich wrote: > > Allow manual override of the tick_do_timer_cpu. > > While not necessarily harmful, doing jiffies updates on an application cpu > does cause some extra overhead that HPC benchmarking people notice. They > prefer to have OS activity isolated to certain cpus. They like reproducibility > of results, and having jiffies updates bouncing around introduces variability.
I really wonder about this changelog. The only case where jiffies updates bounces around is the NOHZ case. In all other modes (periodic or highres) the boot cpu gets the do_timer() duty and it's never assigned to any other cpu.
So what's the point of this exercise? Moving it away from CPU0 for acedemic reasons or what?
Thanks,
tglx
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