linux-kernel - Re: [PATCH] perf record: mmap output file

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Message-ID: <20131015132003.GF2402@gmail.com>
Date:	Tue, 15 Oct 2013 15:20:03 +0200
From:	Ingo Molnar <mingo@...nel.org>
To:	Jiri Olsa <jolsa@...hat.com>
Cc:	Namhyung Kim <namhyung@...nel.org>,
	David Ahern <dsahern@...il.com>, acme@...stprotocols.net,
	linux-kernel@...r.kernel.org,
	Frederic Weisbecker <fweisbec@...il.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Mike Galbraith <efault@....de>,
	Stephane Eranian <eranian@...gle.com>
Subject: Re: [PATCH] perf record: mmap output file - v2


* Jiri Olsa <jolsa@...hat.com> wrote:

> On Tue, Oct 15, 2013 at 09:25:40AM +0200, Ingo Molnar wrote:
> > 
> > * Namhyung Kim <namhyung@...nel.org> wrote:
> > 
> > > > 3)
> > > >
> > > > The rec->bytes_at_mmap_start field feels a bit weird. If I read the code 
> > > > correctly, in every 'perf record' invocation, rec->bytes_written starts at 
> > > > 0 - i.e. we don't have repeat invocations of cmd_record().
> > > 
> > > rec->bytes_written is updated when it writes to the output file for 
> > > synthesizing COMM/MMAP events (this mmap output is not used at that 
> > > time).
> > 
> > Btw., while looking into it, I think advance_output() needlessly 
> > obfuscates as well:
> > 
> > static void advance_output(struct perf_record *rec, size_t size)
> > {
> >         rec->bytes_written += size;
> > }
> > 
> > that code should just be written open coded.
> > 
> > So I think all this needs a few good rounds of cleanups, before we can 
> > complicate it with a new feature. (the cleanups can be on top of the 
> > feature, if they go in at the same time.)
> 
> I sent some file code cleanup week ago, I'll rebase and resend it soon:
>
> http://marc.info/?l=linux-kernel&m=138113836428425&w=2

Nice!

> it's mostly about centralizing the code into file object.. got no 
> comments so far

Too much development going on I suspect :-)

Thanks,

	Ingo
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