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SubjectRe: [tip:timers/urgent] tick: Cleanup NOHZ per cpu data on cpu down


On 05/13/2013 03:10 PM, Thomas Gleixner wrote:
> On Mon, 13 May 2013, Prarit Bhargava wrote:
>> Thomas, while this does fix up the NULL pointer issue, I think you've introduced
>> a new bug in the schedule timer code.
>
> I don't think that I introduced a new bug. I'm quite sure that change
> unearthed another issue which was papered over by the stale data.
>
> That memset is putting the data structure into the same state as we
> have on boot. From tick-sched perspective cpu onlining is not
> different between boot and an offline/online cycle
>
>> While doing up and downs on the same CPU, I now occasionally see long delays in
>> the up and down...
>
>> [ 81.744565] smpboot: Booting Node 1 Processor 19 APIC 0x28
>> [ 82.848591] smpboot: CPU 19 is now offline
>>
>> Long delay in bringing CPU "up"
>>
>> [ 89.826533] smpboot: Booting Node 1 Processor 19 APIC 0x28
>> [ 84.905358] smpboot: CPU 19 is now offline
>> [ 87.565274] smpboot: Booting Node 1 Processor 19 APIC 0x28
>
> Errm, the timestamps are random. -ENOTUSEFUL
>

I'm always saying my computer is full of lies ;)

Here's the bottom line. The patch included in this thread plus the patch you
pointed me to here

http://marc.info/?l=linux-kernel&m=136847403809031&w=2

seem to resolve the cpu up/down + thermal interrupt issues that I've been seeing.

So thank you :)

Tested-by: Prarit Bhargava <prarit@redhat.com>

P.


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