From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from sc8-sf-mx1-b.sourceforge.net ([10.3.1.11] helo=sc8-sf-mx1.sourceforge.net) by sc8-sf-list1.sourceforge.net with esmtp (Exim 4.30) id 1BQpLG-0004jC-1V for user-mode-linux-devel@lists.sourceforge.net; Thu, 20 May 2004 08:20:18 -0700 Received: from mail.gmx.de ([213.165.64.20] helo=mail.gmx.net) by sc8-sf-mx1.sourceforge.net with smtp (Exim 4.30) id 1BQpLE-00056U-Qc for user-mode-linux-devel@lists.sourceforge.net; Thu, 20 May 2004 08:20:17 -0700 Message-ID: <00c801c43e7e$f0262690$2000000a@schlepptopp> From: "roland" References: Subject: Re: [uml-devel] [PATCH] host context switch reduction MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit 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: Thu, 20 May 2004 17:27:17 +0200 To: Henrik Nordstrom Cc: Laurent Vivier , Jeff Dike , user-mode-linux-devel@lists.sourceforge.net > What can be said is that applications running on the host is by far not as > dependent on context switching responsiveness to "feel good", and a CPU > hog in one UML does not cause any noticeable amount of extra context > switches, not much different from a CPU hog on the host in terms of > performance. mh - maybe i don`t understand you completely right here - but - for me, most hogging processes in uml produces a gazillion of context-switches on the host. if i run getpid on the host, i cannot see (vmstat) a noticeable raise in the amount of context switches. if i run getpid inside an uml - i see cs on the host raise from ~400 to ~230000 !! the same getpid in a sysemu-patched uml/host results in a raise from ~400 to ~173000 cs - so this is noticeably better. similar things happen with other "hogs" (idle state is always ~400 cs on host, cs rate is from vmstat output on the host) : "while true; do /bin/true; done" host: ~ 2000 uml: ~ 24000 uml-sysemu: ~ 17000 "while true; do find /; done" host: up to ~ 24000 (alternating very much - didn`t measure average value) uml: up to ~ 60000 ( " ) uml-sysemu: up to ~ 48000 ( " ) "dd if=/dev/urandom of=/dev/null" host: no noticeably differnce uml: ~ 16000 uml-sysemu ~ 8500 regards roland ----- Original Message ----- From: "Henrik Nordstrom" To: "roland" Cc: "Laurent Vivier" ; "Jeff Dike" ; Sent: Thursday, May 20, 2004 4:12 PM Subject: Re: [uml-devel] [PATCH] host context switch reduction > On Thu, 20 May 2004, roland wrote: > > > if i run a getpid-loop inside one uml, the other uml`s behaviour becomes > > quite sluggish - this doesn`t seem to have a relation to laurents patch - i > > just recognized this for the first time, because i never did getpid-loops > > inside a uml. :) > > I would suspect this is due to the high dependency on context switching by > UML in system calls.. but I do not have a clearcut explanation. > > What can be said is that applications running on the host is by far not as > dependent on context switching responsiveness to "feel good", and a CPU > hog in one UML does not cause any noticeable amount of extra context > switches, not much different from a CPU hog on the host in terms of > performance. > > Regards > Henrik > ------------------------------------------------------- This SF.Net email is sponsored by: Oracle 10g Get certified on the hottest thing ever to hit the market... Oracle 10g. Take an Oracle 10g class now, and we'll give you the exam FREE. http://ads.osdn.com/?ad_id=3149&alloc_id=8166&op=click _______________________________________________ User-mode-linux-devel mailing list User-mode-linux-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel