linux-kernel - Re: Can context switches be faster?

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <452E9E47.8070306@nortel.com>
Date:	Thu, 12 Oct 2006 13:57:59 -0600
From:	"Chris Friesen" <cfriesen@...tel.com>
To:	John Richard Moser <nigelenki@...cast.net>
CC:	linux-kernel@...r.kernel.org
Subject: Re: Can context switches be faster?

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.

Chris
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/