From: Jeremy Fitzhardinge <jeremy@goop.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@elte.hu>,
Linus Torvalds <torvalds@linux-foundation.org>,
Martin Bligh <mbligh@google.com>,
Peter Zijlstra <peterz@infradead.org>,
Martin Bligh <mbligh@mbligh.org>,
linux-kernel@vger.kernel.org,
Thomas Gleixner <tglx@linutronix.de>,
Andrew Morton <akpm@linux-foundation.org>,
prasad@linux.vnet.ibm.com,
Mathieu Desnoyers <compudj@krystal.dyndns.org>,
"Frank Ch. Eigler" <fche@redhat.com>,
David Wilder <dwilder@us.ibm.com>,
hch@lst.de, Tom Zanussi <zanussi@comcast.net>,
Steven Rostedt <srostedt@redhat.com>
Subject: Re: [RFC PATCH 1/3] Unified trace buffer
Date: Thu, 25 Sep 2008 16:04:09 -0700 [thread overview]
Message-ID: <48DC18E9.7000007@goop.org> (raw)
In-Reply-To: <alpine.DEB.1.10.0809251840430.32742@gandalf.stny.rr.com>
Steven Rostedt wrote:
> On Fri, 26 Sep 2008, Ingo Molnar wrote:
>
>> Firstly they need a low-frequency (10khz-100khz) shared clock line
>> across all CPUs. A single line - and since it's low frequency it could
>> be overlaid on some existing data line and filtered out. That works
>> across NUMA nodes as well and physics allows it to be nanosec accurate
>> up to dozens of meters or so.
>>
>
> Can this possibly be true? I mean, light travels only one foot every
> nanosecond. Can it really keep nanosecond accuracy up to dozens of meters
> away?
Sure. NTP keeps machines within 1ms (or better) of each other even
though the network latency is much higher and jittery.
J
next prev parent reply other threads:[~2008-09-25 23:04 UTC|newest]
Thread overview: 109+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-09-24 5:10 [RFC PATCH 0/3] An Unified tracing buffer (attempt) Steven Rostedt
2008-09-24 5:10 ` [RFC PATCH 1/3] Unified trace buffer Steven Rostedt
2008-09-24 15:03 ` Peter Zijlstra
2008-09-24 15:44 ` Steven Rostedt
2008-09-25 10:38 ` Ingo Molnar
2008-09-24 15:47 ` Martin Bligh
2008-09-24 16:11 ` Peter Zijlstra
2008-09-24 16:24 ` Linus Torvalds
2008-09-24 16:37 ` Steven Rostedt
2008-09-24 16:56 ` Martin Bligh
2008-09-24 17:25 ` Linus Torvalds
2008-09-24 18:01 ` Mathieu Desnoyers
2008-09-24 20:49 ` Linus Torvalds
2008-09-24 16:26 ` Steven Rostedt
2008-09-24 16:49 ` Martin Bligh
2008-09-24 17:36 ` Linus Torvalds
2008-09-24 17:49 ` Steven Rostedt
2008-09-24 20:23 ` Linus Torvalds
2008-09-24 20:37 ` David Miller
2008-09-24 20:48 ` Steven Rostedt
2008-09-24 20:51 ` Martin Bligh
2008-09-24 21:24 ` Frank Ch. Eigler
2008-09-24 21:33 ` Steven Rostedt
2008-09-24 20:47 ` Steven Rostedt
2008-09-24 21:03 ` Martin Bligh
2008-09-24 21:17 ` Steven Rostedt
2008-09-24 21:51 ` Steven Rostedt
2008-09-25 10:41 ` Peter Zijlstra
2008-09-25 14:33 ` Martin Bligh
2008-09-25 14:53 ` Peter Zijlstra
2008-09-25 15:05 ` Linus Torvalds
2008-09-25 15:25 ` Martin Bligh
2008-09-25 15:36 ` Ingo Molnar
2008-09-25 16:23 ` Mathieu Desnoyers
2008-09-25 16:32 ` Steven Rostedt
2008-09-25 17:20 ` Mathieu Desnoyers
2008-09-25 17:32 ` Steven Rostedt
2008-09-25 16:40 ` Linus Torvalds
2008-09-25 16:53 ` Steven Rostedt
2008-09-25 17:07 ` Linus Torvalds
2008-09-25 19:55 ` Ingo Molnar
2008-09-25 20:12 ` Ingo Molnar
2008-09-25 20:24 ` Linus Torvalds
2008-09-25 20:29 ` Linus Torvalds
2008-09-25 20:47 ` Steven Rostedt
2008-09-25 21:01 ` Steven Rostedt
2008-09-25 21:10 ` Ingo Molnar
2008-09-25 21:16 ` Ingo Molnar
2008-09-25 21:41 ` Ingo Molnar
2008-09-25 21:56 ` Ingo Molnar
2008-09-25 21:58 ` Linus Torvalds
2008-09-25 22:14 ` Ingo Molnar
2008-09-25 23:33 ` Linus Torvalds
2008-09-27 17:16 ` Ingo Molnar
2008-09-27 17:36 ` Ingo Molnar
2008-09-27 17:38 ` Steven Rostedt
2008-09-27 17:50 ` Peter Zijlstra
2008-09-27 18:18 ` Steven Rostedt
2008-09-27 18:42 ` Ingo Molnar
2008-09-25 20:52 ` Ingo Molnar
2008-09-25 21:14 ` Jeremy Fitzhardinge
2008-09-25 21:15 ` Martin Bligh
2008-09-25 20:29 ` Mathieu Desnoyers
2008-09-25 20:20 ` Ingo Molnar
2008-09-25 21:02 ` Jeremy Fitzhardinge
2008-09-25 21:55 ` Linus Torvalds
2008-09-25 22:25 ` Ingo Molnar
2008-09-25 22:45 ` Steven Rostedt
2008-09-25 23:04 ` Jeremy Fitzhardinge [this message]
2008-09-25 23:25 ` Ingo Molnar
2008-09-26 14:04 ` Thomas Gleixner
2008-09-25 22:39 ` Jeremy Fitzhardinge
2008-09-25 22:55 ` Ingo Molnar
2008-09-26 1:17 ` Jeremy Fitzhardinge
2008-09-26 1:27 ` Steven Rostedt
2008-09-26 1:49 ` Jeremy Fitzhardinge
2008-09-25 22:59 ` Steven Rostedt
2008-09-26 1:27 ` Jeremy Fitzhardinge
2008-09-26 1:35 ` Steven Rostedt
2008-09-26 2:07 ` Jeremy Fitzhardinge
2008-09-26 2:25 ` Steven Rostedt
2008-09-26 5:31 ` Jeremy Fitzhardinge
2008-09-26 10:41 ` Steven Rostedt
2008-09-25 15:26 ` Steven Rostedt
2008-09-25 17:22 ` Linus Torvalds
2008-09-25 17:39 ` Steven Rostedt
2008-09-25 18:14 ` Linus Torvalds
2008-09-25 15:20 ` Steven Rostedt
2008-09-24 17:54 ` Martin Bligh
2008-09-24 18:04 ` Martin Bligh
2008-09-24 20:39 ` Linus Torvalds
2008-09-24 20:56 ` Martin Bligh
2008-09-24 21:08 ` Steven Rostedt
2008-09-24 20:30 ` Linus Torvalds
2008-09-24 20:53 ` Mathieu Desnoyers
2008-09-24 22:28 ` Linus Torvalds
2008-09-24 22:41 ` Linus Torvalds
2008-09-25 17:15 ` Mathieu Desnoyers
2008-09-25 17:29 ` Linus Torvalds
2008-09-25 17:42 ` Mathieu Desnoyers
2008-09-25 16:37 ` Mathieu Desnoyers
2008-09-25 16:49 ` Linus Torvalds
2008-09-25 17:02 ` Steven Rostedt
2008-09-24 16:13 ` Mathieu Desnoyers
2008-09-24 16:31 ` Steven Rostedt
2008-09-24 16:39 ` Peter Zijlstra
2008-09-24 16:51 ` Mathieu Desnoyers
2008-09-24 5:10 ` [RFC PATCH 2/3] ftrace: combine some print formating Steven Rostedt
2008-09-24 5:10 ` [RFC PATCH 3/3] ftrace: hack in the ring buffer Steven Rostedt
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