Hi Stefane,
Thanks for this. Am I to understand that the original purpose of
pfm_arch_start is to just flip the enable bits? Is counting supposed
to be enabled after arch_restore_pmcs? My question is really, what is
the counting state of the PMU supposed to be after restore? I read the
below as restore is supposed to write+start the PMC's immediately.
It's an interesting case on the SiCortex box, because the in-core
PMU's have no enable bits (only domain bits) but the off-core PMU has
a global enable bit, which need not be twiddled, as one can write 0's
to the PMC's there and it won't count.
Thanks.
Phil
On Mar 24, 2008, at 6:03 PM, stephane eranian wrote:
> Hello Phil,
>
> pfm_arch_start() is not called during context switch. It is used only
> during pfm_start() and on interrupts on certain architectures.
>
> pfm_restore_pmcs() is used on context switch to restore the pmcs
> (config) registers.
>
> If all pfm_arch_start() does is to restore the pmcs, then it may as
> well
> call pfm_arch_restore_pmcs() instead of re-implementing the same
> thing.
>
>
>
> On Mon, Mar 24, 2008 at 8:17 PM, Philip Mucci <[EMAIL PROTECTED]>
> wrote:
>> Hi Stefane,
>>
>> I'm trying to decipher the difference between these two. Currently on
>> MIPS as there is no enable bit, these are both identical. Basically:
>>
>> for (i = 0; i < max_pmc; i++) {
>> if (test_bit(i, set->used_pmcs))
>> pfm_arch_write_pmc(ctx, i, set->pmcs[i]);
>> }
>>
>> However, in looking at the comments in the code, I have a concern
>> that
>> they may both be being called on pfm_ctxsw() and thus I'm doing
>> double
>> writes to the registers. Can you comment on this?
>>
>> Phil
>>
>>
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