From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
To: Oleg Nesterov <oleg@redhat.com>,
Steven Rostedt <rostedt@goodmis.org>,
Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Ingo Molnar <mingo@elte.hu>, Anton Arapov <anton@redhat.com>,
Frank Eigler <fche@redhat.com>, Josh Stone <jistone@redhat.com>,
"Suzuki K. Poulose" <suzuki@in.ibm.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH 6/6] uprobes/perf: Always increment trace_uprobe->nhit
Date: Mon, 4 Feb 2013 21:56:11 +0530 [thread overview]
Message-ID: <20130204162611.GB28145@linux.vnet.ibm.com> (raw)
In-Reply-To: <20130204151850.GA6641@redhat.com>
* Oleg Nesterov <oleg@redhat.com> [2013-02-04 16:18:50]:
> On 02/04, Srikar Dronamraju wrote:
> >
> > * Oleg Nesterov <oleg@redhat.com> [2013-01-31 20:18:32]:
> >
> > > Move tu->nhit++ from uprobe_trace_func() to uprobe_dispatcher().
> > >
> > > ->nhit counts how many time we hit the breakpoint inserted by this
> > > uprobe, we do not want to loose this info if uprobe was enabled by
> > > sys_perf_event_open().
> > >
> >
> > Though I dont see a problem with this change, It seems unnecessary for
> > me.
> >
> > Info from nhits is mostly for /sys/kernel/debug/tracing/uprobe_profile
>
> It is only for uprobe_profile, yes, and it is useful. Why should we hide
> this info if this uprobe is used by perf?
Fine with me.
Steve, Masami, Do you have comments/suggestions on this.
(Since kprobe_profile just accounts for kprobetracer and doesnt account
for perf record.)
May we should make a similar change in kprobetracer to keep things
similar.
--
Thanks and Regards
Srikar Dronamraju
>
> > I am not sure how sys_perf_event_open() is making use of this?
>
> I hope I'll send the final series today. From the changelog of the patch
> which actually turns the filtering on:
>
> Testing:
>
> # perf probe -x /lib/libc.so.6 syscall
>
> # perl -e 'syscall -1 while 1' &
> [1] 530
>
> # perf record -e probe_libc:syscall perl -e 'syscall -1 for 1..10; sleep 1'
>
> # perf report --show-total-period
> 100.00% 10 perl libc-2.8.so [.] syscall
>
> Before this patch:
>
> # cat /sys/kernel/debug/tracing/uprobe_profile
> /lib/libc.so.6 syscall 79291
>
> A huge ->nrhit == 79291 reflects the fact that the background process
> 530 constantly hits this breakpoint too, even if doesn't contribute to
> the output.
>
> After the patch:
>
> # cat /sys/kernel/debug/tracing/uprobe_profile
> /lib/libc.so.6 syscall 10
>
> This shows that only the target process was punished by int3.
>
> Oleg.
>
> --
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next prev parent reply other threads:[~2013-02-04 16:28 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-31 19:17 [PATCH 0/6] uprobes/tracing: cleanups and minor fixes Oleg Nesterov
2013-01-31 19:18 ` [PATCH 1/6] uprobes/tracing: Fix dentry/mount leak in create_trace_uprobe() Oleg Nesterov
2013-01-31 19:18 ` [PATCH 2/6] uprobes/tracing: Fully initialize uprobe_trace_consumer before uprobe_register() Oleg Nesterov
2013-01-31 19:18 ` [PATCH 3/6] uprobes/tracing: Ensure inode != NULL in create_trace_uprobe() Oleg Nesterov
2013-02-04 10:48 ` Srikar Dronamraju
2013-01-31 19:18 ` [PATCH 4/6] uprobes/tracing: Introduce is_trace_uprobe_enabled() Oleg Nesterov
2013-02-04 16:12 ` Srikar Dronamraju
2013-01-31 19:18 ` [PATCH 5/6] uprobes/tracing: Kill uprobe_trace_consumer, embed uprobe_consumer into trace_uprobe Oleg Nesterov
2013-02-04 16:59 ` Srikar Dronamraju
2013-02-04 17:20 ` Oleg Nesterov
2013-02-11 9:18 ` Srikar Dronamraju
2013-02-11 9:19 ` Srikar Dronamraju
2013-01-31 19:18 ` [PATCH 6/6] uprobes/perf: Always increment trace_uprobe->nhit Oleg Nesterov
2013-02-04 11:17 ` Srikar Dronamraju
2013-02-04 15:18 ` Oleg Nesterov
2013-02-04 16:26 ` Srikar Dronamraju [this message]
2013-02-04 16:34 ` Steven Rostedt
2013-02-11 9:19 ` Srikar Dronamraju
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