linux-kernel - Re: [PATCH 0/2] perf: add sort by inclusive time functionality (v2)

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Date:	Mon, 12 Mar 2012 11:05:16 -0700
From:	Arun Sharma <asharma@...com>
To:	Namhyung Kim <namhyung.kim@....com>
CC:	Frederic Weisbecker <fweisbec@...il.com>,
	Ingo Molnar <mingo@...e.hu>, <linux-kernel@...r.kernel.org>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Mike Galbraith <efault@....de>,
	Paul Mackerras <paulus@...ba.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Stephane Eranian <eranian@...gle.com>,
	Tom Zanussi <tzanussi@...il.com>,
	<linux-perf-users@...r.kernel.org>
Subject: Re: [PATCH 0/2] perf: add sort by inclusive time functionality (v2)

On 3/12/12 12:15 AM, Namhyung Kim wrote:

>
> I think it's because of the shared hist_entry. If a callchain is a
> subset of another, it will be marked as inclusive so that it cannot be
> contributed to total period. Say, there're two chains - X (a -> b -> c)
> and Y (a -> b), once __hists__add_entry_inclusive() was called on X, we
> have:
>
> a -> b -> c
> a -> b (inclusive)
> a (inclusive)
>
> And then, calling the function on Y should make:
>
> a -> b
> a (inclusive)
>
> However, since both callchains are in tree already they'll be shared and
> marked *inclusive*. Thus the total period will not increased at all for
> Y. Also I guess the reverse case - add Y first, and then X - will have
> the same result.

Thanks for figuring this out. Looks like using a single bit 
(he->inclusive) is insufficient. How about:

struct hist_entry {
	u64                     period;
         u64                     period_self;
	..
};

Normal mode: period_self == period.
Inclusive mode: period_self will be zero for inclusive hist_entries.
Shared entries: we sum up both period and period_self.

We can then compute total_period by summing up period_self.

  -Arun

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