Thanks for your answer.
On 09/30/2014 02:55 PM, Namhyung Kim wrote:
Hi Taeung,
On Tue, 30 Sep 2014 12:19:41 +0900, taeung wrote:
Hi,
I have two questions about 'zeroing of samples' in 'perf top'.
I knew if I use 'perf top', I can see a performance counter profile in
real time.
But I can't find a difference between 'perf top -a' and 'perf top
--zero'.
After 'perf top' is run , I press key 'z' to toggle zeroing of samples.
But I don't know a difference between when I press key 'z' and before
I did it.
1. What is 'Zero history' ?
(I saw it in Documentation/perf-top.txt that '--zero' option is 'Zero
history across display updates.')
2. What do 'zeroing of samples' mean ?
It seems that both questions are same.
The way perf top works is collecting samples and cumulate them into the
history (with decaying). So it basically shows current value + old
value. With -z option, it won't use old values.
And yes, one cannot easily find a difference between -z option and
normal output. So we might need a visual cue as Arnaldo suggested
earlier. Are you interested in implementing it?
Yes , I really wanna implement it
to easily find a difference between -z option and default option.
At last, I understand what -z option mean.
As what Arnaldo suggested , I'll implement it.
Thanks,
Taeung
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