Messages in this thread | | | Subject | Re: [patch, v2.6.22-rc6] sys_time() speedup | From | john stultz <> | Date | Tue, 26 Jun 2007 09:59:24 -0700 |
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On Tue, 2007-06-26 at 16:58 +0200, Ingo Molnar wrote: > * Mark Lord <lkml@rtr.ca> wrote: > > > Ingo Molnar wrote: > > >Subject: [patch] sys_time() speedup > > >From: Ingo Molnar <mingo@elte.hu> > > > > > >improve performance of sys_time(). sys_time() returns time in seconds, > > >but it does so by calling do_gettimeofday() and then returning the > > >tv_sec portion of the GTOD time. But the data structure "xtime", which > > >is updated by every timer/scheduler tick, already offers HZ granularity > > >time. > > > > How well synchronized is xtime with real-time ? > > it's updated by every jiffy.
Well, NTP_INTERVAL_LENGTH to be specific which is every jiffie with one exception: With dynticks this is a bit more complicated, and xtime is updated only twice a second.
thanks -john
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