Re: [RFCv2 0/8] perf tool: Add new event group management

From: Peter Zijlstra
Date: Mon Apr 16 2012 - 10:24:12 EST

On Mon, 2012-04-16 at 14:16 +0200, Jiri Olsa wrote:
> also, any thoughts about the displaying question? ;)
> > I'm looking on how to present this data in perf and it seems we need
> > to reset all siblings once we read/store them (in kernel) to the
> > leader sample.
> >
> > My current thinking is to store siblings' sum values for each
> > hists entry of the sample (perf report count unit) .. and display
> > them in similar way we display callchains: for each hists entry
> > display the sum value for each sibling.
> >
> > Could you provide more of your world examples? Your expectations about
> > presenting this..
> >
> > Maybe we want to make the reset optional, and do some do some other
> > math with siblings' values..?

My thought was to do the exact same thing with it that we do with the
regular multi-event thing (which could be improved too). Simply create
individual event views with variable period based on the sample delta
for that particular event.

So suppose you have a group of 3 with only the leader sampling and you
get tuples like:

IP=x {1000, 500, 750}
IP=y {2000, 800, 1500}
IP=z {3000, 1100, 2000}

This could be decomposed into 3 event views like:

IP=x,period=1000 IP=x,period=500 IP=x,period=750
IP=y,period=1000 IP=y,period=300 IP=y,period=750
IP=z,period=1000 IP=z,period=300 IP=z,period=500

Just like what would've happened if you'd used multiple events like:

attr = {
.freq = 1,
.sample_period = 1000,

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