From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
To: rostedt <rostedt@goodmis.org>
Cc: linux-kernel <linux-kernel@vger.kernel.org>,
Ingo Molnar <mingo@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Masami Hiramatsu <mhiramat@kernel.org>,
Arnaldo Carvalho de Melo <acme@redhat.com>,
Jiri Olsa <jolsa@redhat.com>, Namhyung Kim <namhyung@kernel.org>,
Yordan Karadzhov <y.karadz@gmail.com>,
Tzvetomir Stoyanov <tz.stoyanov@gmail.com>,
Tom Zanussi <zanussi@kernel.org>,
Jason Behmer <jbehmer@google.com>,
Julia Lawall <julia.lawall@inria.fr>,
Clark Williams <williams@redhat.com>,
bristot <bristot@redhat.com>, Daniel Wagner <wagi@monom.org>,
Darren Hart <dvhart@vmware.com>, Jonathan Corbet <corbet@lwn.net>,
"Suresh E. Warrier" <warrier@linux.vnet.ibm.com>
Subject: Re: [RFC][PATCH] ring-buffer: Have nested events still record running time stamp
Date: Thu, 25 Jun 2020 09:53:15 -0400 (EDT) [thread overview]
Message-ID: <126813531.12266.1593093195147.JavaMail.zimbra@efficios.com> (raw)
In-Reply-To: <20200625094454.732790f7@oasis.local.home>
----- On Jun 25, 2020, at 9:44 AM, rostedt rostedt@goodmis.org wrote:
> From: "Steven Rostedt (VMware)" <rostedt@goodmis.org>
>
> [ SEVEN YEAR PROBLEM SOLVED! ]
>
> Up until now, if an event is interrupted while it is recorded by an
> interrupt, and that interrupt records events, the time of those events will
> all be the same. This is because events only record the delta of the time
> since the previous event (or beginning of a page), and to handle updating
> the time keeping for that of nested events is extremely racy. After years of
> thinking about this and several failed attempts, I finally have a solution
> to solve this puzzle.
Out of curiosity, considering that LTTng has solved this problem 10+ years ago
with a simpler concurrency-friendly time-stamping model, why not simply use it
rather than add complexity to the current ftrace timestamp scheme ?
Thanks,
Mathieu
--
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com
next prev parent reply other threads:[~2020-06-25 13:53 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-25 13:44 [RFC][PATCH] ring-buffer: Have nested events still record running time stamp Steven Rostedt
2020-06-25 13:53 ` Mathieu Desnoyers [this message]
2020-06-25 14:37 ` Steven Rostedt
2020-06-25 16:42 ` Korben Rusek
2020-06-25 18:12 ` Steven Rostedt
2020-06-25 17:55 ` Mathieu Desnoyers
2020-06-25 18:35 ` Steven Rostedt
2020-06-25 19:35 ` Mathieu Desnoyers
2020-06-25 19:58 ` Steven Rostedt
2020-06-26 2:36 ` Steven Rostedt
2020-06-26 3:35 ` Steven Rostedt
2020-06-26 13:58 ` Steven Rostedt
2020-06-26 18:13 ` Mathieu Desnoyers
2020-06-26 18:58 ` Steven Rostedt
2020-06-26 19:39 ` Steven Rostedt
2020-06-30 0:21 ` Steven Rostedt
2020-06-30 3:13 ` Mathieu Desnoyers
2020-06-30 3:26 ` Steven Rostedt
2020-06-25 19:04 ` Steven Rostedt
2020-06-25 19:58 ` Mathieu Desnoyers
2020-06-25 20:42 ` Steven Rostedt
2020-06-25 19:09 ` Steven Rostedt
2020-06-25 20:03 ` Mathieu Desnoyers
2020-06-25 18:09 ` Steven Rostedt
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