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Re: [PATCH -tip 0/4] perf-probe updates: string support, etc.
- From: Arnaldo Carvalho de Melo <acme at infradead dot org>
- To: Masami Hiramatsu <masami dot hiramatsu dot pt at hitachi dot com>
- Cc: Chase Douglas <chase dot douglas at canonical dot com>, Ingo Molnar <mingo at elte dot hu>, lkml <linux-kernel at vger dot kernel dot org>, Paul Mackerras <paulus at samba dot org>, Peter Zijlstra <peterz at infradead dot org>, Mike Galbraith <efault at gmx dot de>, Frederic Weisbecker <fweisbec at gmail dot com>, systemtap <systemtap at sources dot redhat dot com>, DLE <dle-develop at lists dot sourceforge dot net>
- Date: Mon, 5 Jul 2010 21:54:09 -0300
- Subject: Re: [PATCH -tip 0/4] perf-probe updates: string support, etc.
- References: <20100519195717.2885.90799.stgit@localhost6.localdomain6> <56FC4434-EA6C-4A0C-A95B-3D7BE818774B@canonical.com> <20100705174450.GB23506@ghostprotocols.net>
Em Mon, Jul 05, 2010 at 02:44:50PM -0300, Arnaldo Carvalho de Melo escreveu:
> Em Mon, Jul 05, 2010 at 10:30:47AM -0400, Chase Douglas escreveu:
> > On May 19, 2010, at 3:57 PM, Masami Hiramatsu wrote:
> > > Here is a series of patches which improves perf probe to
> > > add below features. I cleared some coding style issues.
> > > - String support, which enables dynamic events to trace string
> > > variables instead of its address.
> > > - Fixed-index array entry support, which allows user to trace
> > > an array entry with digit index, e.g. array[0].
> > > - Global/static variable support, which allows user to trace
> > > global or static variables, as same as local one.
> > What's the status of these patches? They seem very useful to me, but I
> > don't see them in Arnaldo's tree at git.kernel.org.
> Thanks for reminding me about these ones, will look at them to get them
> in perf/core.
Masami, I fixed up a minor conflict and while trying it this happened:
[root@emilia ~]# perf probe -a 'bio_split bi->bi_io_vec[0]'
kprobe_events file does not exist - please rebuild kernel with CONFIG_KPROBE_EVENT.
Error: Failed to add events. (-1)
But on a second try:
[root@emilia ~]# l /sys/kernel/debug/tracing/kprobe_events
-rw-r--r-- 1 root root 0 Jul 5 18:37 /sys/kernel/debug/tracing/kprobe_events
[root@emilia ~]# cat /sys/kernel/debug/tracing/kprobe_events
[root@emilia ~]#
[root@emilia ~]# perf probe -a 'bio_split bi->bi_io_vec[0]'
Add new event:
probe:bio_split (on bio_split with bi_io_vec=bi->bi_io_vec[0])
You can now use it on all perf tools, such as:
perf record -e probe:bio_split -aR sleep 1
[root@emilia ~]# cat /sys/kernel/debug/tracing/kprobe_events
p:probe/bio_split bio_split bi_io_vec=+0(+72(%di)):u64
[root@emilia ~]#
I'll push it as is, posting the pull request with the patches today,
please check if everything is ok and send fixups if needed,
Thanks,
- Arnaldo