linux-kernel - Re: [RFC PATCH v3 00/37] perf tools: introduce 'perf bpf' command to load eBPF programs.

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Date:	Tue, 19 May 2015 14:42:11 -0700
From:	Alexei Starovoitov <ast@...mgrid.com>
To:	Arnaldo Carvalho de Melo <acme@...nel.org>
CC:	Namhyung Kim <namhyung@...nel.org>, Wang Nan <wangnan0@...wei.com>,
	paulus@...ba.org, a.p.zijlstra@...llo.nl, mingo@...hat.com,
	jolsa@...nel.org, dsahern@...il.com, daniel@...earbox.net,
	brendan.d.gregg@...il.com, masami.hiramatsu.pt@...achi.com,
	lizefan@...wei.com, linux-kernel@...r.kernel.org, pi3orama@....com
Subject: Re: [RFC PATCH v3 00/37] perf tools: introduce 'perf bpf' command
 to load eBPF programs.

On 5/19/15 2:10 PM, Arnaldo Carvalho de Melo wrote:
>
> This all should use infrastructure in perf for symbol resolving,
> callcahins, etc.

yes. 100%

> Right, but if we do a:
>
> perf script -i perf.data bpf_file.c
>
> Then there would be a short circuit effect of just doing the
> aggregation and/or reporting.

That can work, but I don't see why I would use bpf for
scripting on top of perf.data. If trace is already collected,
the existing perl/python scripts will work fine.

> Well, we could have a tee like mode where perf.data file could be
> generated so that we could run it again after doing some change on the
> aggregation code, so that we wouldn't have to re-run the data collection
> parts, that could be about some condition hard to capture, etc.

true, but again I don't think in such scenario you'd need bpf.
bpf is needed when the number of events is huge and the user
needs to aggregate/process them in-kernel.

>> I guess I'm saying let's not get too much ahead of ourselves ;)
>
> No problem, but then we need to talk at this moment not to add new stuff
> that we think should not be added, like 'perf bpf' :-)

ahh, that's where you going :) Sure. I don't mind avoiding that
unbearable abbreviation if we can :)
'perf script file.[oc]' command line works for me.

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