From: "Frédéric Weisbecker" <fweisbec@gmail.com>
To: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>,
"K.Prasad" <prasad@linux.vnet.ibm.com>,
Arjan van de Ven <arjan@infradead.org>,
"Frank Ch. Eigler" <fche@redhat.com>,
linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH] perf_core: provide a kernel-internal interface to get to performance counters
Date: Mon, 5 Oct 2009 11:24:53 +0200 [thread overview]
Message-ID: <c62985530910050224u5e755808jc2a25c3dd5c172da@mail.gmail.com> (raw)
In-Reply-To: <20091005085551.GA31147@elte.hu>
2009/10/5 Ingo Molnar <mingo@elte.hu>:
>
> * Peter Zijlstra <peterz@infradead.org> wrote:
>> Non-trivial.
>>
>> Something like this would imply a single output channel for all these
>> CPUs, and we've already seen that stuffing too many CPUs down one such
>> channel (using -M) leads to significant performance issues.
>
> We could add internal per cpu buffering before it hits any globally
> visible output channel. (That has come up when i talked to Frederic
> about the function tracer.) We could even have page sized output (via
> the introduction of a NOP event that fills up to the next page edge).
That looks good for the counting/sampling fast path, but would that scale
once it comes to reordering in the globally visible output channel?
Such a union has its costs.
next prev parent reply other threads:[~2009-10-05 9:25 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-09-25 10:25 [RFC PATCH] perf_core: provide a kernel-internal interface to get to performance counters Arjan van de Ven
2009-09-25 10:44 ` Frederic Weisbecker
2009-09-25 11:42 ` Peter Zijlstra
2009-09-26 16:03 ` Frank Ch. Eigler
2009-09-26 16:11 ` Arjan van de Ven
2009-09-26 16:20 ` Frank Ch. Eigler
2009-09-26 18:32 ` K.Prasad
2009-09-26 18:48 ` Arjan van de Ven
2009-10-01 7:25 ` Ingo Molnar
2009-10-01 8:16 ` K.Prasad
2009-10-01 8:53 ` Ingo Molnar
2009-10-01 10:01 ` K.Prasad
2009-10-01 10:28 ` Ingo Molnar
2009-10-04 22:28 ` Frederic Weisbecker
2009-10-05 9:55 ` Ingo Molnar
2009-10-05 10:13 ` Frédéric Weisbecker
2009-10-05 7:53 ` Peter Zijlstra
2009-10-05 8:55 ` Ingo Molnar
2009-10-05 9:24 ` Frédéric Weisbecker [this message]
2009-10-05 9:48 ` Ingo Molnar
2009-10-05 10:08 ` Frédéric Weisbecker
2009-11-21 13:36 ` [tip:perf/core] perf/core: Provide " tip-bot for Arjan van de Ven
2010-02-05 15:47 ` [RFC PATCH] perf_core: provide " Christoph Hellwig
2010-02-05 17:59 ` john smith
2010-02-06 6:24 ` Arjan van de Ven
2010-02-06 11:46 ` Frederic Weisbecker
2010-02-06 14:18 ` Peter Zijlstra
2010-02-06 16:08 ` Frederic Weisbecker
2010-02-07 17:01 ` Ingo Molnar
2010-01-25 5:10 john smith
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