Corey,
AFAIK, PMD registers can be read at 5 different times:
- on pfm_read_pmds()
- on context switch save
- set switch save
- on counter overflow to record a sample
- on unload for flush PMU state to software
In all situations, interrupts are indeed disabled. So you should not need
getcpu/putcpu.
On Tue, Jul 15, 2008 at 6:46 PM, Corey J Ashford <[EMAIL PROTECTED]> wrote:
> Hi Stephane,
>
> I was not aware that interrupts are disabled during the call the pmd_sread
> call, thanks for catching that. Is that also the case for the
> enable_counters and disable_counters calls as well?
>
> Regards,
>
> - Corey
>
> Corey Ashford
> Software Engineer
> IBM Linux Technology Center, Linux Toolchain
> Beaverton, OR
> 503-578-3507
> [EMAIL PROTECTED]
>
>
>
>
> "stephane eranian" <[EMAIL PROTECTED]>
> 07/15/2008 03:24 AM
> Please respond to
> [EMAIL PROTECTED]
>
>
> To
> Corey J Ashford/Beaverton/[EMAIL PROTECTED]
> cc
> perfmon2-devel@lists.sourceforge.net
> Subject
> Re: [PATCH 5/5] fixes for full perfmon2 on POWER
>
>
>
>
>
>
> Corey,
>
>
> I don't understand this patch.
> You say:
> "This patch fixes a problem with accessing the array of cpu-specific PMU
> counters, where there was a race condition that could occur where we
> acquire the cpu number, and then have the cpu switch out from underneath
> us. Using get_cpu()/put_cpu() fixes this problem because get_cpu()
> disables preemption until put_cpu() is called again."
>
> What do you mean by "switch from underneath". AFAIK, pmd_sread() is called
> with interrupts masked. I thought, this was enough to prevent any
> preemption?
>
>
>
> On Mon, Jul 14, 2008 at 11:50 PM, Corey Ashford <[EMAIL PROTECTED]>
> wrote:
>> This fixes an issue on POWER4 and POWER6 where PMU exceptions need to be
>> disabled when the context is in masked mode.
>>
>> --
>> Corey Ashford
>> Software Engineer
>> IBM Linux Technology Center, Linux Toolchain
>> Beaverton, OR
>> 503-578-3507
>> [EMAIL PROTECTED]
>>
>
>
>
-------------------------------------------------------------------------
This SF.Net email is sponsored by the Moblin Your Move Developer's challenge
Build the coolest Linux based applications with Moblin SDK & win great prizes
Grand prize is a trip for two to an Open Source event anywhere in the world
http://moblin-contest.org/redirect.php?banner_id=100&url=/
_______________________________________________
perfmon2-devel mailing list
perfmon2-devel@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/perfmon2-devel
