From: Frederic Weisbecker <fweisbec@gmail.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@elte.hu>, Paul Mackerras <paulus@samba.org>,
Arnaldo Carvalho de Melo <acme@infradead.org>,
Steven Rostedt <rostedt@goodmis.org>,
Thomas Gleixner <tglx@linutronix.de>,
linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH 5/5] perf: Implement perf_output_addr()
Date: Wed, 19 May 2010 11:03:20 +0200 [thread overview]
Message-ID: <20100519090319.GJ5704@nowhere> (raw)
In-Reply-To: <1274255882.5605.10216.camel@twins>
On Wed, May 19, 2010 at 09:58:02AM +0200, Peter Zijlstra wrote:
> On Wed, 2010-05-19 at 09:21 +0200, Frederic Weisbecker wrote:
>
> > I'm still not sure what you mean here by this multiplexing. Is
> > this about per cpu multiplexing?
>
> Suppose there's two events attached to the same tracepoint. Will you
> write the tracepoint twice and risk different data in each, or will you
> do it once and copy it into each buffer?
The only different data we risk in each is the timestamp, which is
something we can probably fetch once before actually filling the
buffers.
> > There is another problem. We need something like
> > perf_output_discard() in case the filter reject the event (which
> > must be filled for this check to happen).
>
> Yeah, I utterly hate that, I opted to let anything with a filter take
> the slow path. Not only would I have to add a discard, but I'd have to
> decrement the counter as well, which is a big no-no.
That makes it complicated. But for now we don't have much other solutions.
next prev parent reply other threads:[~2010-05-19 9:03 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-05-18 13:32 [PATCH 0/5] Optimize perf ring-buffer Peter Zijlstra
2010-05-18 13:32 ` [PATCH 1/5] perf: Disallow mmap() on per-task inherited events Peter Zijlstra
2010-05-19 7:19 ` Frederic Weisbecker
2010-05-25 0:55 ` Paul Mackerras
2010-05-25 8:19 ` Peter Zijlstra
2010-05-18 13:33 ` [PATCH 2/5] perf: Remove IRQ-disable from the perf_output path Peter Zijlstra
2010-05-18 13:33 ` [PATCH 3/5] perf: Convert the perf output buffer to local_t Peter Zijlstra
2010-05-18 13:33 ` [PATCH 4/5] perf: Avoid local_xchg Peter Zijlstra
2010-05-18 13:33 ` [RFC PATCH 5/5] perf: Implement perf_output_addr() Peter Zijlstra
2010-05-18 14:09 ` Peter Zijlstra
2010-05-19 7:21 ` Frederic Weisbecker
2010-05-19 7:58 ` Peter Zijlstra
2010-05-19 9:03 ` Frederic Weisbecker [this message]
2010-05-19 14:47 ` Steven Rostedt
2010-05-19 15:05 ` Peter Zijlstra
2010-05-19 15:38 ` Steven Rostedt
2010-05-19 15:50 ` Peter Zijlstra
2010-05-19 16:08 ` Steven Rostedt
2010-05-19 16:15 ` Peter Zijlstra
2010-05-19 16:27 ` Steven Rostedt
2010-05-19 16:34 ` Peter Zijlstra
2010-05-19 7:14 ` [PATCH 0/5] Optimize perf ring-buffer Frederic Weisbecker
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