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From: Paulo Marques <pmarques@grupopie.com>
To: Kristian Benoit <kbenoit@opersys.com>
Cc: paulmck@us.ibm.com, Karim Yaghmour <karim@opersys.com>,
	linux-kernel@vger.kernel.org, bhuey@lnxw.com, andrea@suse.de,
	tglx@linutronix.de, mingo@elte.hu, bruce@andrew.cmu.edu,
	nickpiggin@yahoo.com.au, ak@muc.de, sdietrich@mvista.com,
	dwalker@mvista.com, hch@infradead.org, akpm@osdl.org,
	Philippe Gerum <rpm@xenomai.org>
Subject: Re: PREEMPT_RT vs I-PIPE: the numbers, part 2
Date: Thu, 23 Jun 2005 15:48:33 +0100	[thread overview]
Message-ID: <42BACBC1.2090101@grupopie.com> (raw)
In-Reply-To: <1119460803.5825.13.camel@localhost>


Kristian Benoit wrote:
> [...]
> Your analysis is correct, but with 600,000 samples, it is possible that
> we got 2 peeks (perhaps not maximum), one on the logger and one on the
> target. So in my point of view, the maximum value is probably somewhere
> between 55us / 2 and 55us - 7us. And probably closer to 55us / 2.

I could provide some help here, by providing the schematics and firmware 
for having a microcontroller do the pulse timing part. The schematics 
should be extremely simple, and easy to build in a breadboard (no 
soldering required) with standard parts from electronics resellers.

With a hardware solution we could measure the *actual* target latency 
with sub-microsecond accuracy, and do some fun stuff too, like 
triggering the pulse at random intervals in a given range, etc.

The microcontroller would then connect to the logger (or the HOST in 
your setup, and avoid an extra computer) through a serial port to report 
the measurements.

Is this something that could be useful, or do you think this is just 
overkill?

-- 
Paulo Marques - www.grupopie.com

It is a mistake to think you can solve any major problems
just with potatoes.
Douglas Adams

  parent reply	other threads:[~2005-06-23 14:49 UTC|newest]

Thread overview: 61+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-06-20 17:13 PREEMPT_RT vs I-PIPE: the numbers, part 2 Kristian Benoit
2005-06-20 18:31 ` Bill Huey
2005-06-22 16:00   ` Karim Yaghmour
2005-06-22 19:29     ` Bill Huey
2005-06-22 20:05       ` Ingo Molnar
2005-06-22 20:39         ` Karim Yaghmour
2005-06-22 22:04           ` Ingo Molnar
2005-06-22 23:03             ` Lee Revell
2005-06-22 23:52               ` Karim Yaghmour
2005-06-22 23:38             ` Karim Yaghmour
2005-06-22 23:57               ` Andrea Arcangeli
2005-06-23  0:05               ` Daniel Walker
2005-06-23  0:48                 ` Karim Yaghmour
2005-06-23  0:06               ` Ingo Molnar
2005-06-23  0:47                 ` Karim Yaghmour
2005-06-23  0:55                   ` Bill Huey
2005-06-23  1:09                     ` Karim Yaghmour
2005-06-23  1:15                       ` Bill Huey
2005-06-23  1:47                         ` Karim Yaghmour
2005-06-23  0:59                   ` David Lang
2005-06-23  1:22                     ` Karim Yaghmour
2005-06-23  1:42                       ` David Lang
2005-06-23  2:09                         ` Karim Yaghmour
2005-06-23  2:15                           ` David Lang
2005-06-23  1:34                   ` Ingo Molnar
2005-06-23  2:02                     ` Karim Yaghmour
2005-06-23  3:57                       ` Lee Revell
2005-06-23  4:13                         ` Karim Yaghmour
2005-06-22 20:10       ` Karim Yaghmour
2005-06-22 20:15         ` Bill Huey
2005-06-21  1:55 ` Paul E. McKenney
2005-06-21  2:29   ` Karim Yaghmour
2005-06-22  1:19     ` Paul E. McKenney
2005-06-22 15:31       ` Karim Yaghmour
2005-06-22 15:27         ` Kristian Benoit
2005-06-22 16:27         ` Paul E. McKenney
2005-06-22 17:20           ` Kristian Benoit
2005-06-22 17:34             ` Ingo Molnar
2005-06-22 17:40               ` Ingo Molnar
2005-06-22 18:12                 ` Karim Yaghmour
2005-06-22 18:14                   ` Ingo Molnar
2005-06-22 19:04                     ` Karim Yaghmour
2005-06-22 18:50             ` Paul E. McKenney
2005-06-22 19:04               ` Ingo Molnar
2005-06-22 20:17                 ` Karim Yaghmour
2005-06-22 20:22                   ` Ingo Molnar
2005-06-22 21:03                     ` Karim Yaghmour
2005-06-22 21:10                       ` Ingo Molnar
2005-06-22 21:32                         ` Karim Yaghmour
2005-06-22 22:41                       ` Ingo Molnar
2005-06-22 23:02                         ` Karim Yaghmour
2005-06-22 21:20                 ` Paul E. McKenney
2005-06-22 19:08               ` Karim Yaghmour
2005-06-23 14:48             ` Paulo Marques [this message]
2005-06-22 17:58           ` Karim Yaghmour
2005-06-22 18:47             ` Paul E. McKenney
2005-06-22 19:16               ` Karim Yaghmour
2005-06-22 21:23                 ` Paul E. McKenney
2005-06-22 17:17         ` Lee Revell
2005-06-22 17:32           ` Karim Yaghmour
2005-06-29  7:43           ` PREEMPT_RT & threading IRQ 0 Ingo Molnar

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