From: John Richard Moser <nigelenki@comcast.net>
To: Chris Friesen <cfriesen@nortel.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: Can context switches be faster?
Date: Thu, 12 Oct 2006 16:23:29 -0400 [thread overview]
Message-ID: <452EA441.6070703@comcast.net> (raw)
In-Reply-To: <452E9E47.8070306@nortel.com>
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Chris Friesen wrote:
> John Richard Moser wrote:
>
>> Linux ported onto the L4-Iguana microkernel is reported to be faster
>> than the monolith[1]; it's not like microkernels are faster, but the
>> L4-Iguana apparently just has super awesome context switching code:
>>
>> Wombat's context-switching overheads as measured by lmbench on an
>> XScale processor are up to thirty times less than those of native
>> Linux, thanks to Wombat profiting from the implementation of fast
>> context switches in L4-embedded.
>
> The Xscale is a fairly special beast, and it's context-switch times are
> pretty slow by default.
>
> Here are some context-switch times from lmbench on a modified 2.6.10
> kernel. Times are in microseconds:
>
> cpu clock speed context switch
> pentium-M 1.8GHz 0.890
> dual-Xeon 2GHz 7.430
> Xscale 700MHz 108.2
> dual 970FX 1.8GHz 5.850
> ppc 7447 1GHz 1.720
>
> Reducing the Xscale time by a factor of 30 would basically bring it into
> line with the other uniprocessor machines.
>
That's a load more descriptive :D
0.890 uS, 0.556uS/cycle, that's barely 2 cycles you know. (Pentium M)
PPC performs similarly, 1 cycle should be about 1uS.
> Chris
>
- --
We will enslave their women, eat their children and rape their
cattle!
-- Bosc, Evil alien overlord from the fifth dimension
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next prev parent reply other threads:[~2006-10-12 20:23 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-10-12 15:44 Can context switches be faster? John Richard Moser
2006-10-12 15:53 ` John Richard Moser
2006-10-12 17:19 ` Russell King
2006-10-12 18:25 ` John Richard Moser
2006-10-12 18:37 ` Arjan van de Ven
2006-10-12 18:56 ` John Richard Moser
2006-10-12 19:02 ` Arjan van de Ven
2006-10-13 11:05 ` James Courtier-Dutton
2006-10-13 14:51 ` Chase Venters
2006-10-12 18:20 ` Phillip Susi
2006-10-12 18:29 ` John Richard Moser
2006-10-13 2:53 ` Andrew James Wade
2006-10-13 5:29 ` John Richard Moser
2006-10-13 16:56 ` Andrew James Wade
2006-10-13 17:24 ` John Richard Moser
2006-10-12 19:57 ` Chris Friesen
2006-10-12 20:23 ` John Richard Moser [this message]
2006-10-12 20:29 ` Arjan van de Ven
2006-10-12 20:36 ` John Richard Moser
2006-10-12 20:35 ` Jeremy Fitzhardinge
2006-10-13 23:32 ` Andreas Mohr
2006-10-13 23:47 ` David Lang
2006-10-14 0:14 ` Jeremy Fitzhardinge
2006-10-14 0:30 ` Alan Cox
2006-10-14 0:14 ` Jeremy Fitzhardinge
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