linux-kernel - Re: [RFC PATCH -v2 0/4] Persistent events

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Message-ID: <20120816214103.GE16308@aftab.osrc.amd.com>
Date:	Thu, 16 Aug 2012 23:41:03 +0200
From:	Borislav Petkov <bp@...64.org>
To:	Steven Rostedt <rostedt@...dmis.org>
Cc:	Jonathan Corbet <corbet@....net>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...nel.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH -v2 0/4] Persistent events

On Thu, Aug 16, 2012 at 05:13:33PM -0400, Steven Rostedt wrote:
> BTW, we already have a persistent buffering in the kernel. It's used
> by ftrace. What about having perf use that buffering for persistent
> events? Or is there some other issues about using it.

Not that I know of.

I coded this with the perf ring buffer now. If only there was one ring
buffer in the kernel.. /me ducks and hides.

Ok, with perf I can read out the events programmatically by mmaping the
per-CPU buffer with perf_mmap. How do you do that in ftrace? Any code
pointers I can stare at?

> I'm currently working on having perf read ftrace data, so in the near
> future, I plan on having some RFC patches to have perf reading from
> this buffer anyway.

Are you saying the ftrace buffer would be mmappable too now?

Btw, I wanted to hear your opinion on patch 1/4 since it touches
ftrace/trace_events code. Can you please look at it and tell me if its
ok?

Thanks.

-- 
Regards/Gruss,
Boris.

Advanced Micro Devices GmbH
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