Re: perf record of multiple events: disable callgraph for some events

[Arnaldo Carvalho de Melo <acme@kernel.org>]

Em Fri, Oct 09, 2015 at 04:08:10PM +0200, Milian Wolff escreveu:
> On Sonntag, 4. Oktober 2015 17:40:59 CEST Arnaldo Carvalho de Melo wrote:
> > Em Sun, Oct 04, 2015 at 01:48:21PM +0200, Milian Wolff escreveu:

> > > would it be possible to add a feature to perf to only grab
> > > callgraphs for a certain selection of events? E.g. thinking about
> > > a lock contention profile of a Qt application, I'd listen to

> > > -e syscalls:sys_enter_futex,syscalls:sys_exit_futex

> > > Now, with the dwarf unwinder this easily produces huge data files in the
> > > order of gigabytes. This cost could easily be reduced by a factor of two,
> > > as one only needs the callgraphs for syscalls:sys_enter_futex - the TID
> > > should be enough to find the callgraph for the enter event from the exit
> > > trace point.

> > > Could someone guide me in implementing such a feature to make it possible
> > > to filter the events which trigger the collection of a callgraph? Or is
> > > that already possible somehow?

> > Can you please check if this suits you, it is already in the tree:
> > 
> > commit e637d17757a10732fa5d573c18f20b3cd4d31245
> > Author: He Kuang <hekuang@huawei.com>
> > Date:   Mon Sep 28 03:52:16 2015 +0000
 
> <snip>
 
> Perfect, Thanks Arnaldo for pointing me in that direction, and many thanks to 
> He for implementing it! Works like a charm.
> 
> Does anyone have a suggestion on where to put documentation for this? I'll try 
> to add that then next week, together with the other stuff I've noticed and 
> couldn't find before. Otherwise, I'll put it into the docs for `perf record`'s 
> `--call-graph`.

Works for me. Glad that it worked for you. :-)

- Arnaldo