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

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Message-ID: <4F5E9EB6.6050302@lge.com>
Date:	Tue, 13 Mar 2012 10:11:18 +0900
From:	Namhyung Kim <namhyung.kim@....com>
To:	linux-kernel@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/2] perf: add sort by inclusive time functionality (v2)

2012-03-13 3:05 AM, Arun Sharma wrote:
> 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.
>

Yeah, I agree that we need that kind of code to handle total_period properly. 
Looking forward to your v3 :).

Thanks,
Namhyung


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