Messages in this thread | | | Date | Sat, 3 Sep 2005 03:16:09 -0700 | From | Tony Lindgren <> | Subject | Re: Updated dynamic tick patches |
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On Fri, Sep 02, 2005 at 11:04:32PM +0530, Srivatsa Vaddagiri wrote: > On Thu, Sep 01, 2005 at 04:07:22PM +0300, Tony Lindgren wrote: > > Srivatsa, could you try the dyntick-test.c on your system after booting > > to init=/bin/sh to make the system as idle as possible? > > Tony, > I get this o/p when I run your test on my SMP system with > 2.6.13-mm1 + Con's latest patches (including the most recent > lost tick calculation patch that I posted after that). ... > > Don't see any ERROR status. The negative latencies doesn't seem to sound > good. Do you see them too? I ran your test on my RH9 based T30 and > find several negative latencies there too.
Good, thanks for testing.
> Test: select 3000ms time: 3.000127s latency: 0.000127s status: OK
This is when I started seeing errors. Looks like if the next event from next_timer_interrupt() is longer than HZ and idle HZ is very low, such as 3 - 4 HZ, something gets confused.
I'll be looking into it more a bit later on, but until the problem is solved, we should limit MAX_SKIP_TICKS to HZ/2.
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