Re: [patch 0/4] perf_counter tools: support annotation of live kernel modules

Mike Galbraith
2009-07-02T07:55:53Z

On Thu, 2009-07-02 at 09:42 +0200, Ingo Molnar wrote:

(squirrels suggestions away for later reference)

> Btw, another thing: we are thinking about making -F 1000 (1 KHz
> auto-freq sampling) the default for perf top and perf record. This
> way we'd always gather enough data (and never too much or too little
> data), regardless of the intensity of the workload. Have you played
> with -F before, what's your general experience about it? It's
> particularly useful for 'rare' and highly fluctuating events like
> cache-misses.
>
> Maybe 1KHz is a bit too low - Oprofile defaults to 100000 cycles
> interval by default which is about 10 KHz on a 1GHz box and 30 KHz
> on a 3GHz box. Perhaps 10 KHz is a better default?

My default usage is 1000Hz to keep overhead low. Works fine for me.

-Mike