From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from sc8-sf-mx2-b.sourceforge.net ([10.3.1.12] helo=sc8-sf-mx2.sourceforge.net) by sc8-sf-list1.sourceforge.net with esmtp (Exim 4.30) id 1CEad5-0006hD-Vn for user-mode-linux-devel@lists.sourceforge.net; Mon, 04 Oct 2004 14:44:23 -0700 Received: from bay22-f38.bay22.hotmail.com ([64.4.16.88] helo=hotmail.com) by sc8-sf-mx2.sourceforge.net with esmtp (Exim 4.41) id 1CEacz-0000dl-68 for user-mode-linux-devel@lists.sourceforge.net; Mon, 04 Oct 2004 14:44:23 -0700 From: "Young K" Mime-Version: 1.0 Content-Type: text/plain; format=flowed Message-ID: Subject: [uml-devel] slow execution in uml? Sender: user-mode-linux-devel-admin@lists.sourceforge.net Errors-To: user-mode-linux-devel-admin@lists.sourceforge.net List-Unsubscribe: , List-Id: The user-mode Linux development list List-Post: List-Help: List-Subscribe: , List-Archive: Date: Mon, 04 Oct 2004 17:35:00 -0400 To: user-mode-linux-devel@lists.sourceforge.net hi, folks, i was comparing uml network performance with genuine linux. the experiment i did was to insert time-stamping code in network stack, and see how slower uml is. i was sending 32-byte udp packets to another machine every 10 msec, and used rdtsc to measure the elapsed cpu cycles between sendto() and nf_hook_slow() (which is called inside ip_build_xmit()). what i found was that it took around 29,000 cycles from sendto() to nf_hook_slow() in uml whereas only 2,000 cycles in genuine linux. it looks like a big difference. but i think it's purely code execution without any I/O operation between sendto() to nf_hook_slow(). then, why is it so slow in uml? is there any possible factors that make uml slower? (more cache misses?) i used 2.4.22 for guest os(tt mode) and 2.4.25 for host os, but numbers were pretty much the same when i used other versions of 2.4 kernels for both guest and host. the computer i used for test was P4 2.2 GHz single processor with 512MB, FYI. _________________________________________________________________ Check out Election 2004 for up-to-date election news, plus voter tools and more! http://special.msn.com/msn/election2004.armx ------------------------------------------------------- This SF.net email is sponsored by: IT Product Guide on ITManagersJournal Use IT products in your business? Tell us what you think of them. Give us Your Opinions, Get Free ThinkGeek Gift Certificates! Click to find out more http://productguide.itmanagersjournal.com/guidepromo.tmpl _______________________________________________ User-mode-linux-devel mailing list User-mode-linux-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel