From: Masami Hiramatsu <mhiramat@kernel.org>
To: Arun Kalyanasundaram <arunkaly@google.com>
Cc: Steven Rostedt <rostedt@goodmis.org>,
mhiramat@kernel.org, linux-kernel@vger.kernel.org,
mingo@kernel.org, David Carrillo-Cisneros <davidcc@google.com>
Subject: Re: tracing/kprobes: [Bug] Identical timestamps on two kprobes that are few instructions apart
Date: Mon, 10 Jul 2017 09:18:45 +0900 [thread overview]
Message-ID: <20170710091845.5db494f938a1ab6c8e2b0259@kernel.org> (raw)
In-Reply-To: <CAGjB_BpcrHaRuWQdCmP8_H6k2JUgSwQAt1tm9Kxnm6CyMOc_Ng@mail.gmail.com>
Hello Arun,
On Fri, 7 Jul 2017 16:06:40 -0700
Arun Kalyanasundaram <arunkaly@google.com> wrote:
> Hi Steven,
>
> Thank you very much for your reply. I am using kernel - v4.12-rc3.
>
> I did something like this and see the issue:
> # trace-cmd record -e kprobes:s1 -e kprobes:s2 -- taskset -c 0 my_program
> # ./trace-cmd report -t --cpu 0
>
> The issue is pretty intermittent and only happens when there are a lot
> of samples, and so "my_program" generates a few hundred threads. Any
> pointers on debugging this would be very helpful, or please let me
> know if you want me to collect any log messages.
Ok, so this happens with ftrace+trace-cmd too.
If you run it on x86-64, could you add "-C x86-tsc" and check still
it happens? If not, I guess it happens when it adjusts timestamp.
Thank you,
--
Masami Hiramatsu <mhiramat@kernel.org>
next prev parent reply other threads:[~2017-07-10 0:18 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CAGjB_BpTmk+gvNMpuxWweu1UnzFixPrxKKAxzJxm2svz+-FVXg@mail.gmail.com>
2017-07-07 19:01 ` Steven Rostedt
2017-07-07 23:06 ` Arun Kalyanasundaram
2017-07-10 0:18 ` Masami Hiramatsu [this message]
2017-07-10 17:38 ` Arun Kalyanasundaram
2017-07-09 12:51 ` Masami Hiramatsu
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