Messages in this thread | | | Subject | Re: High CPU load when machine is idle (related to PROBLEM: Unusually high load average when idle in 2.6.35, 2.6.35.1 and later) | From | Peter Zijlstra <> | Date | Mon, 25 Oct 2010 12:12:53 +0200 |
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On Fri, 2010-10-22 at 16:03 -0700, Venkatesh Pallipadi wrote: > I started making small changes to the code, but none of the change helped much. > I think the problem with the current code is that, even though idle CPUs > update load, the fold only happens when one of the CPU is busy > and we end up taking its load into global load. > > So, I tried to simplify things and doing the updates directly from idle loop. > This is only a test patch, and eventually we need to hook it off somewhere > else, instead of idle loop and also this is expected work only as x86_64 > right now. > > Peter: Do you think something like this will work? loadavg went > quite on two of my test systems after this change (4 cpu and 24 cpu).
Not really, CPUs can stay idle for _very_ long times (!x86 cpus that don't have crappy timers like HPET which roll around every 2-4 seconds).
But all CPUs staying idle for a long time is exactly the scenario you fix before using the decay_load_misses() stuff, except that is for the load-balancer per-cpu load numbers not the global cpu load avg. Won't a similar approach work here?
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