Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750729AbWJLUXd (ORCPT ); Thu, 12 Oct 2006 16:23:33 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750840AbWJLUXd (ORCPT ); Thu, 12 Oct 2006 16:23:33 -0400 Received: from alnrmhc13.comcast.net ([206.18.177.53]:15577 "EHLO alnrmhc13.comcast.net") by vger.kernel.org with ESMTP id S1750729AbWJLUXc (ORCPT ); Thu, 12 Oct 2006 16:23:32 -0400 Message-ID: <452EA441.6070703@comcast.net> Date: Thu, 12 Oct 2006 16:23:29 -0400 From: John Richard Moser User-Agent: Thunderbird 1.5.0.7 (X11/20060918) MIME-Version: 1.0 To: Chris Friesen CC: linux-kernel@vger.kernel.org Subject: Re: Can context switches be faster? References: <452E62F8.5010402@comcast.net> <452E9E47.8070306@nortel.com> In-Reply-To: <452E9E47.8070306@nortel.com> X-Enigmail-Version: 0.94.0.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2598 Lines: 69 -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 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 -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.3 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iQIVAwUBRS6kPws1xW0HCTEFAQJnAhAAloJ1KvztR+CiKSvBEvEHUcoUm9HwxpaE WrTKrBxEV36VXgHVzJsqvs6YLzyLhyLWv2YFKlPS6iYyKvwO3v8P54fVPLqZAcAn 7VSAml9wSRt1woh1MxwApDlQO/snf5rAV/+1cuCGXKmpqLAHCGjrMJgn5TEbknCG 9H4Ie5Db6541lO7Zw5rouas03wLVPUU831UCTKJi8ngyx30FNDeaDds9EeYA0Ox/ 5gEOVavkHRV5AJ6GhGtmgEpTdB69oB6nwv07UtuYN7QKC2tJ0E7tomuLeh4mbMM9 N5rV9Q+KzL955HINqQPe5+pF31+W4fQ4zKBzyyz0AQ6BHkyu+v9B371HuIo5RCeV adC5p17PM5Ms819bfB0Nl6WjRhje5ybTDHyKxiNEHQL7T+LCkCjJvDvkeIr33aS2 vcAlFQvk8RYz5bZn1dsJpXfYc0GPH9M93Zf3dOr8syPmzOCFlD3MgWJvcTGlg2fT Lxg5e8MBfjwyZ1XYBouFaY4GlytaebCXT5jXlutZDYQfIIIsHhQ2BV3xCcr2jP5K Q1UmOld8GB+HeHmfvge3/5gXWIQxZx/vgNEm+XPUQk7j0Ei9E4yy/MVdXdx4GKDv uNbclRT3xOlYhsbabGsxunCRok6Ph4eTQPmT3YLO+rpxLq1vyGDW3+kEca6+yCIp WEBb7mlPRaw= =pvD8 -----END PGP SIGNATURE----- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/