linux-kernel - Re: [PATCH v6 13/18] perf: add support for taken branch sampling to perf report

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Message-ID: <20120223181132.GB3571@infradead.org>
Date:	Thu, 23 Feb 2012 16:11:32 -0200
From:	Arnaldo Carvalho de Melo <acme@...hat.com>
To:	Stephane Eranian <eranian@...gle.com>
Cc:	Ingo Molnar <mingo@...e.hu>,
	Roberto Agostino Vitillo <ravitillo@....gov>,
	linux-kernel@...r.kernel.org, peterz@...radead.org,
	robert.richter@....com, ming.m.lin@...el.com, andi@...stfloor.org,
	asharma@...com, vweaver1@...s.utk.edu, khandual@...ux.vnet.ibm.com,
	dsahern@...il.com
Subject: Re: [PATCH v6 13/18] perf: add support for taken branch sampling
	to perf report

Em Thu, Feb 23, 2012 at 05:53:53PM +0100, Stephane Eranian escreveu:
> Ok, so I looked at that today. Adding the feature bit is trivial.
> But what's not easy is to get to the feature bit in perf report
> by the time we need it. Very quickly after parsing the options,
> we setup a bunch of things such as browser mode, sorting
> order based on the -b option. But to get to the feature bit, we
> would need to wait until after the session is created in
> __cmd_report() which is way later.
> 
> So we either hoist perf_session__new() very early, i.e., as soon
> as we have the filename or we write yet another parse_header()
> function just to get to the feature bits. I would rather choose the
> first option. But none is really pretty...
> 
> Arnaldo, any better idea?

Humm, lemme see...


By the time we need it is when we do setup_sorting, right? Perhaps we
can delay that till after we do perf_session__new and thus have read the
headers...

/me looks at the code.

- Arnaldo
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