From: Steven Rostedt <rostedt@goodmis.org>
To: Claudio <claudio.fontana@gliwa.com>
Cc: Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
linux-kernel@vger.kernel.org
Subject: Re: ftrace global trace_pipe_raw
Date: Wed, 16 Jan 2019 08:47:02 -0500 [thread overview]
Message-ID: <20190116084702.6d6ce764@gandalf.local.home> (raw)
In-Reply-To: <5af4b871-41dd-219b-f78e-3a60ea570160@gliwa.com>
On Wed, 16 Jan 2019 09:00:00 +0100
Claudio <claudio.fontana@gliwa.com> wrote:
> Indeed the perf event interface would be awesome, if only it would support tracing all processes.
>
> Unfortunately for my use case, it can only trace one process on any cpus, or all processes on one (1) cpu.
>
> I guess for some kind of security concerns..
Not security, but performance.
Serialized writes are best done on serialized instances (per cpu or a
single task). Having all tasks on all CPUs write to a single location
is a huge detriment to performance, and has a significant impact. Which
is why the buffer you are asking for doesn't exist.
-- Steve
>
> I'll take a look at how much work it would be to extend the interface for the any process/any cpu use case.
>
> Ciao and thank you,
>
> Claudio
>
>
next prev parent reply other threads:[~2019-01-16 13:47 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-06 6:22 ftrace performance (sched events): cyclictest shows 25% more latency Claudio
2018-07-06 21:24 ` Steven Rostedt
2018-07-06 21:39 ` Steven Rostedt
2018-07-06 22:00 ` Steven Rostedt
2018-07-09 10:06 ` Claudio
2018-07-09 14:53 ` Claudio
2018-07-09 15:11 ` Steven Rostedt
2018-07-09 15:32 ` Steven Rostedt
2018-07-24 9:58 ` ftrace global trace_pipe_raw Claudio
2018-07-24 14:23 ` Steven Rostedt
2018-07-24 14:25 ` Steven Rostedt
2018-07-24 15:30 ` Claudio
2018-12-19 11:32 ` Claudio
2018-12-19 16:37 ` Steven Rostedt
2019-01-16 8:00 ` Claudio
2019-01-16 13:47 ` Steven Rostedt [this message]
2018-07-24 9:59 ` Claudio
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