From: Daniel Bristot de Oliveira <bristot@redhat.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>,
Tom Zanussi <zanussi@kernel.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: Enable histograms for events/ftrace/timerlat and osnoise
Date: Mon, 27 Mar 2023 14:37:11 +0200 [thread overview]
Message-ID: <9a1bb631-587c-9771-99b7-55623c67bb83@redhat.com> (raw)
In-Reply-To: <ead16e4f-a05b-8b76-e1e6-52223effd6c5@redhat.com>
On 3/24/23 17:13, Daniel Bristot de Oliveira wrote:
> Hi Steven
>
> I would like to collect histograms from timerlat and osnoise tracers event,
> but I cannot collect them because they are not tracepoints but... tracer
> events. So...
>
> # ls /sys/kernel/tracing/events/ftrace/timerlat/
> format hist
>
> no hist, filter, trigger files...
Ooop, the hist file exists, what is missing is the trigger file, which is
used to enable the histogram...
it seems that the "limitation" is around TRACE_EVENT_FL_IGNORE_ENABLE flag, and
the fact that ftrace events cannot be enabled/disabled...
but wait, as the hist file exist, is there any other way to enable
the histogram? (or should we disable hist files for !TRACE_EVENT_FL_IGNORE_ENABLE)?
am I missing something?
> How hard would it be to enable histograms to the ftrace/osnoise and
> ftrace/timerlat events?
>
> This will allow me to reduce the overhead of rtla timerlat and rtla osnoise
> tools...
>
> Thanks in advance, Stephen!
> -- Denny
next prev parent reply other threads:[~2023-03-27 12:38 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-24 16:13 Enable histograms for events/ftrace/timerlat and osnoise Daniel Bristot de Oliveira
2023-03-27 12:37 ` Daniel Bristot de Oliveira [this message]
2023-03-27 15:27 ` Steven Rostedt
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