Messages in this thread | | | Date | Tue, 08 Mar 2005 15:23:28 -0800 | From | George Anzinger <> | Subject | Re: [PATCH] clean up FIXME in do_timer_interrupt |
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Lee Revell wrote: > On Fri, 2005-03-04 at 12:58 -0800, George Anzinger wrote: > >>Lee Revell wrote: >> >>>On Fri, 2005-03-04 at 02:28 -0800, George Anzinger wrote: >>>The thing that brought this code to my attention is that with PREEMPT_RT >>>this happens to be the longest non-preemptible code path in the kernel. >>>On my 1.3 Ghz machine set_rtc_mmss takes about 50 usecs, combined with >>>the rest of timer irq we end up disabling preemption for about 90 usecs. >>>Unfortunately I don't have the trace anymore. >>> >>>Anyway the upshot is if we hung this off a timer it looks like we would >>>improve the worst case latency with PREEMPT_RT by almost 50%. Unless >>>there is some reason it has to be done synchronously of course. >> >>Well, it does have to be done at the right WRT the second, but I suspect we can >>hit that as well with a timer as it is hit now. Also, if we are _really_ off >>the mark, this can be defered till the next second. >> > > > Do you have a patch?
Not at the moment, but I will work one up. > > Andrew merged my trivial patch to clean up the logic, but a real fix > would be better. > > Lee >
-- George Anzinger george@mvista.com High-res-timers: http://sourceforge.net/projects/high-res-timers/
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