On Friday, November 16, 2007 9:25 AM, Eric Saxe wrote:
> Li, Aubrey wrote:
>>
>> Sorry, I didn't catch your point. We have only one probe, from which
>> we only have a timestamp. Next time the probe fired, the key of the
>> association is changed. How to track an interval between the first
>> time and the second time of the association with the same key?
>>
> I guess you need to track the old state and time for the CPU. I think
> you can do that in some associative arrays:
>
>>> cpu_change_speed
> {
> ...
> this->cpu = (processorid_t)arg1; /* arg1 == CPU
> for which we
> are changing speed */
> this->newspd = (uint_t)arg2; /* arg2 == New speed */
>
> this->oldspd = current_speeds[this->cpu];
> current_speeds[this->cpu] = this->newspd;
>
> this->now = timestamp;
> time_at_speed = this->now - state_times[this->cpu];
> state_times[this->cpu] = this->now;
>
> @pstate_times[this->oldspd, this->cpu] = sum(time_at_speed); }
>
> ... or to get aggregate times (across all CPUs) I think you should be
> able to do:
>
> @pstate_times[this->oldspd] = sum(time_at_speed);
>
Eric,
This is almost I have tried. The result is unsatisfied for me.
As you know, P-state switching frequency is low.
So,
1) from time to time, P-state only switches one time in the sampling
period, you'll get nothing.
This->oldspd = 0
2) as I said, we have only one probe.
The first time_at_speed is always wrong and we don't know the
initial timestamp we should subtract.
Thanks,
-Aubrey
