From: Christoph Lameter <cl@linux-foundation.org>
To: "Luck, Tony" <tony.luck@intel.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>,
Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
Ingo Molnar <mingo@elte.hu>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
Steven Rostedt <rostedt@goodmis.org>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Thomas Gleixner <tglx@linutronix.de>,
David Miller <davem@davemloft.net>,
Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [RFC patch 15/15] LTTng timestamp x86
Date: Fri, 17 Oct 2008 14:36:56 -0500 [thread overview]
Message-ID: <48F8E958.5080907@linux-foundation.org> (raw)
In-Reply-To: <57C9024A16AD2D4C97DC78E552063EA3532D455F@orsmsx505.amr.corp.intel.com>
Luck, Tony wrote:
> Even one line bouncing between cpus can be a performamce disaster.
> You'll probably hit a serious wall somewhere between 8 and 16
> cpus (ia64 has code that looks a lot like this in the gettimeofday()
> path because it does not synchronize cpu cycle counters ... some
The code exist by necessity because some systems do not have synchronized ITCs
and one would not have time go backward. The cmpxchg there is usually switched
off. Its horrible in terms of scaling to large numbers of processor and also
horrible in terms of clock accuracy.
next prev parent reply other threads:[~2008-10-17 19:39 UTC|newest]
Thread overview: 94+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-10-16 23:27 [RFC patch 00/15] Tracer Timestamping Mathieu Desnoyers
2008-10-16 23:27 ` Mathieu Desnoyers
2008-10-16 23:27 ` [RFC patch 01/15] get_cycles() : kconfig HAVE_GET_CYCLES Mathieu Desnoyers
2008-10-16 23:27 ` Mathieu Desnoyers
2008-10-16 23:27 ` [RFC patch 02/15] get_cycles() : x86 HAVE_GET_CYCLES Mathieu Desnoyers
2008-10-16 23:27 ` Mathieu Desnoyers
2008-10-16 23:27 ` [RFC patch 03/15] get_cycles() : sparc64 HAVE_GET_CYCLES Mathieu Desnoyers
2008-10-16 23:27 ` Mathieu Desnoyers
2008-10-17 2:48 ` [RFC patch 03/15] get_cycles() : sparc64 HAVE_GET_CYCLES (update) Mathieu Desnoyers
2008-10-17 2:48 ` Mathieu Desnoyers
2008-10-17 2:57 ` David Miller
2008-10-16 23:27 ` [RFC patch 04/15] get_cycles() : powerpc64 HAVE_GET_CYCLES Mathieu Desnoyers
2008-10-16 23:27 ` Mathieu Desnoyers
2008-10-17 0:26 ` Paul Mackerras
2008-10-17 0:43 ` [RFC patch 04/15] get_cycles() : powerpc64 HAVE_GET_CYCLES (update) Mathieu Desnoyers
2008-10-17 0:43 ` Mathieu Desnoyers
2008-10-17 0:54 ` Paul Mackerras
2008-10-17 1:42 ` David Miller
2008-10-17 2:08 ` Mathieu Desnoyers
2008-10-17 2:08 ` Mathieu Desnoyers
2008-10-17 2:33 ` David Miller
2008-10-16 23:27 ` [RFC patch 05/15] get_cycles() : MIPS HAVE_GET_CYCLES_32 Mathieu Desnoyers
2008-10-16 23:27 ` Mathieu Desnoyers
2008-10-26 10:18 ` Ralf Baechle
2008-10-26 10:18 ` Ralf Baechle
2008-10-26 20:39 ` Mathieu Desnoyers
2008-10-16 23:27 ` [RFC patch 06/15] LTTng build Mathieu Desnoyers
2008-10-16 23:27 ` Mathieu Desnoyers
2008-10-17 8:10 ` KOSAKI Motohiro
2008-10-17 16:18 ` Mathieu Desnoyers
2008-10-16 23:27 ` [RFC patch 07/15] LTTng timestamp Mathieu Desnoyers
2008-10-16 23:27 ` Mathieu Desnoyers
2008-10-17 8:15 ` KOSAKI Motohiro
2008-10-17 16:23 ` Mathieu Desnoyers
2008-10-17 16:23 ` Mathieu Desnoyers
2008-10-16 23:27 ` [RFC patch 08/15] LTTng - Timestamping Mathieu Desnoyers
2008-10-16 23:27 ` Mathieu Desnoyers
2008-10-16 23:27 ` [RFC patch 09/15] LTTng mips export hpt frequency Mathieu Desnoyers
2008-10-16 23:27 ` Mathieu Desnoyers
2008-10-16 23:27 ` [RFC patch 10/15] LTTng timestamp mips Mathieu Desnoyers
2008-10-16 23:27 ` Mathieu Desnoyers
2008-10-16 23:27 ` [RFC patch 11/15] LTTng timestamp powerpc Mathieu Desnoyers
2008-10-16 23:27 ` Mathieu Desnoyers
2008-10-16 23:27 ` [RFC patch 12/15] LTTng timestamp sparc64 Mathieu Desnoyers
2008-10-16 23:27 ` Mathieu Desnoyers
2008-10-16 23:27 ` [RFC patch 13/15] LTTng timestamp sh Mathieu Desnoyers
2008-10-16 23:27 ` Mathieu Desnoyers
2008-10-16 23:27 ` [RFC patch 14/15] LTTng - TSC synchronicity test Mathieu Desnoyers
2008-10-16 23:27 ` Mathieu Desnoyers
2008-10-16 23:27 ` [RFC patch 15/15] LTTng timestamp x86 Mathieu Desnoyers
2008-10-16 23:27 ` Mathieu Desnoyers
2008-10-17 0:08 ` Linus Torvalds
2008-10-17 0:12 ` Linus Torvalds
2008-10-17 1:28 ` Mathieu Desnoyers
2008-10-17 2:19 ` Luck, Tony
2008-10-17 2:19 ` Luck, Tony
2008-10-17 17:25 ` Steven Rostedt
2008-10-17 18:08 ` Luck, Tony
2008-10-17 18:42 ` Mathieu Desnoyers
2008-10-17 18:58 ` Luck, Tony
2008-10-17 20:23 ` Mathieu Desnoyers
2008-10-17 23:52 ` Luck, Tony
2008-10-18 17:01 ` Mathieu Desnoyers
2008-10-18 17:01 ` Mathieu Desnoyers
2008-10-18 17:35 ` Linus Torvalds
2008-10-18 17:50 ` Ingo Molnar
2008-10-22 16:19 ` Mathieu Desnoyers
2008-10-22 15:53 ` Mathieu Desnoyers
2008-10-20 18:07 ` Luck, Tony
2008-10-22 16:51 ` Mathieu Desnoyers
2008-10-17 19:17 ` Steven Rostedt
2008-10-20 20:10 ` Linus Torvalds
2008-10-20 20:10 ` Linus Torvalds
2008-10-20 21:38 ` john stultz
2008-10-20 22:06 ` Linus Torvalds
2008-10-20 22:17 ` Ingo Molnar
2008-10-20 22:17 ` Ingo Molnar
2008-10-20 22:29 ` H. Peter Anvin
2008-10-20 22:29 ` H. Peter Anvin
2008-10-21 18:10 ` Bjorn Helgaas
2008-10-23 15:47 ` Linus Torvalds
2008-10-23 16:39 ` H. Peter Anvin
2008-10-23 21:54 ` Paul Mackerras
2008-10-20 23:47 ` john stultz
2008-10-20 23:47 ` john stultz
2008-10-22 17:05 ` Mathieu Desnoyers
2008-10-17 19:36 ` Christoph Lameter [this message]
2008-10-17 7:59 ` [RFC patch 00/15] Tracer Timestamping Peter Zijlstra
2008-10-20 20:25 ` Mathieu Desnoyers
2008-10-20 20:25 ` Mathieu Desnoyers
2008-10-21 0:20 ` Nicolas Pitre
2008-10-21 1:32 ` Mathieu Desnoyers
2008-10-21 2:32 ` Nicolas Pitre
2008-10-21 4:05 ` Mathieu Desnoyers
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