Re: perf: h/w counters not counted and no error/info reported to user

From: Ingo Molnar
Date: Mon May 30 2011 - 04:22:20 EST



* David Ahern <dsahern@xxxxxxxxx> wrote:

>
>
> On 05/27/2011 03:50 AM, Ingo Molnar wrote:
> >
> > * David Ahern <dsahern@xxxxxxxxx> wrote:
> >
> >> By default (tip-perf-core) perf-stat enables a number of H/W counters:
> >>
> >> perf stat -- sleep 1
> >
> > did you mean to do 'perf stat -a sleep 1' ?
>
> Adding the -a has its own problems. It blocks reading from fd=0
> (stdin); I have to type Ctrl-D to see the results. The FD array
> gets initialized to 0 and some case is not erroring out or setting
> the fd.

Ok, that's a bug (and you sent the fix for it already) - weird that i
havent seen this before, i use perf stat -a sleep 1 type of analysis
all the time.

Thanks,

Ingo
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