Re: perf top -z not working?

[David Ahern <dsahern@gmail.com>]

On 10/22/12 5:50 AM, Ryan Johnson wrote:
>>>> It seems that `perf top -z' does not behave as advertized, at
>>>> least not on the 3.2.0-25 kernel (Ubuntu) that I'm running. The
>>>> man page states that it should "zero history across display
>>>> updates" but the counts still seem to accumulate (the total
>>>> samples reported rises monotonically) and processes still show up
>>>> in the display long after they have exited. Pressing `z' or `Z'
>>>> seems to have no effect, either.
>> Are you using the --tui or --stdio interface? Try with both and check if
>> it works in one of them, I bet the problem is with --tui.
> --stdio does the same, so I'll have to try updating my kernel like
> Chulmin suggested (haven't had time to do that yet)

The kernel has nothing to do with the feature. From builtin-top.c, this 
part is either not happening or more likely not happening correctly.

     if (top->zero)
         symbol__annotate_zero_histogram(symbol, top->sym_evsel->idx);
     else
         symbol__annotate_decay_histogram(symbol, top->sym_evsel->idx);

I recall it working recently - last year or so. Can you try different 
versions -- say 3.0, 3.2, 3.4 and latest? If you have a copy of Linus' 
tree or Arnaldo's git tree it should not take much time.

David