Hi,

I may not be the best one to answer: I use oprofile with regular wake-up and I am testing on long enough use cases so that a wake-up every scheduler tick is sufficient (like "top", it converges in some seconds to the right values).

I don't really have use of performance counter wake-ups and I don't really know what CPU_CYCLES perf counter will bring except more granularity. Maybe something related to Idle time where timer-based oprofile would not execute as we can be tickless.

I could be more interested in more granularity of timer based solution but official guideline may be to use CPU_CYCLES ;-)

So guys, please speak out if you need perf counters in oprofile, if you want more granularity in wake-ups. Or even simply require this interruption from perf counters for other purposes.

Regards

Fred

Frederic Turgis

OMAP Platform Business Unit - OMAP System Engineering - Platform Enablement

Texas Instruments France SA, 821 Avenue Jack Kilby, 06270 Villeneuve Loubet. 036 420 040 R.C.S Antibes. Capital de EUR 753.920

From: David Long [mailto:dave.long@linaro.org]
Sent: Monday, September 26, 2011 7:27 AM
To: Turgis, Frederic
Cc: Bianconi, Cyril; linaro-dev@lists.linaro.org; Michael Hope; Avik Sil; Dave Martin; Christian Robottom Reis; andy.green@linaro.org
Subject: RE: 11.07 oprofile on panda busted?

Andy made an interesting suggestion to me. What if the profile event code allocated all the counters to the requested event. It could reallocate half of them if a second event was also requested, and so on, till we're down to one (unreliably interrupting) counter. Or we could set a limit requiring at least three counters per event.

The problem would still exist, but this should throw the maximum amount of ammunition we have towards minimizing it. Would this be worth the effort to implement?

-dl