linux-kernel - Re: [PATCHvFIXED 7/7] ftrace, perf: Add filter support for function trace event

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Message-ID: <20111224023527.GE28309@somewhere.redhat.com>
Date:	Sat, 24 Dec 2011 03:35:29 +0100
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Jiri Olsa <jolsa@...hat.com>
Cc:	rostedt@...dmis.org, mingo@...hat.com, paulus@...ba.org,
	acme@...stprotocols.net, a.p.zijlstra@...llo.nl,
	linux-kernel@...r.kernel.org, aarapov@...hat.com
Subject: Re: [PATCHvFIXED 7/7] ftrace, perf: Add filter support for function
 trace event

On Thu, Dec 22, 2011 at 04:26:09PM +0100, Jiri Olsa wrote:
> On Thu, Dec 22, 2011 at 01:55:58PM +0100, Jiri Olsa wrote:
> > On Wed, Dec 21, 2011 at 11:07:58PM +0100, Frederic Weisbecker wrote:
> > > On Wed, Dec 21, 2011 at 07:56:31PM +0100, Jiri Olsa wrote:
> > > > Adding support to filter function trace event via perf
> > > > interface. It is now possible to use filter interface
> > > > in the perf tool like:
> > > > 
> > > >   perf record -e ftrace:function --filter="(ip == mm_*)" ls
> > > > 
> > > > The filter syntax is restricted to the the 'ip' field only,
> > > > and following operators are accepted '==' '!=' '||', ending
> > > > up with the filter strings like:
> > > > 
> > > >   "ip == f1 f2 ..." || "ip != f3 f4 ..." ...
> > > 
> > > Having the functions seperated like this sort of violates the
> > > grammar of the filtering interface.
> > > 
> > > The typical way to do this would have been to stringify the
> > > functions: ip == "f1 f2"
> > > 
> > > I feel a bit uncomfortable with "ip == f1 f2" scheme but perhaps
> > > we can live with that. Especially as otherwise that would
> > > require us to type "ip == \"f1 f2\"" for the whole filtering expression.
> > 
> > ugh, just realized there's a problem with this in the patch actually,
> > and it's not working as expected. I'll send out new version soon.. 
> > 
> > thanks,
> > jirka
> > 
> > > 
> > > Thoughts?
> 
> how about this one.. ;)
> 
> for some reason I presumed ftrace_set_filter would deal with ' '
> as a filter separator.. but it needs to be done before we use
> this function... (ftrace_set_notrace respectively)
> 
> so now you could use one of following:
> 
> perf record -e ftrace:function --filter '(ip == do_execve,sys_*,ext*)' ls
> perf record -e ftrace:function --filter '(ip == "do_execve,sys_*,ext*")' ls
> perf record -e ftrace:function --filter '(ip == "do_execve sys_* ext*")' ls

Nice! ;)

Thanks!
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