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 1BQsAn-0003WD-BL for user-mode-linux-devel@lists.sourceforge.net; Thu, 20 May 2004 11:21:41 -0700 Received: from imap.gmx.net ([213.165.64.20] helo=mail.gmx.net) by sc8-sf-mx1.sourceforge.net with smtp (Exim 4.30) id 1BQsAm-0006o7-NO for user-mode-linux-devel@lists.sourceforge.net; Thu, 20 May 2004 11:21:40 -0700 Message-ID: <01fa01c43e98$4420d510$2000000a@schlepptopp> From: "roland" References: <20040229043549.GA8583@ccure.user-mode-linux.org> <02dc01c43c4a$bb7c0490$2000000a@schlepptopp> <1084831251.1230.4.camel@chartreuse> <03ff01c43c5d$7db6e5e0$2000000a@schlepptopp> <20040518175904.GB29114@ccure.user-mode-linux.org> <1084987654.2250.4.camel@chartreuse> Subject: Re: [uml-devel] [PATCH] host context switch reduction MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" 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 20:28:36 +0200 Content-Transfer-Encoding: quoted-printable To: user-mode-linux-devel@lists.sourceforge.net Cc: Jeff Dike hi, i had a conversation with laurent regarding dynamic toggling of the new sys= emu feature via procfs. >I think switching on/off sysemu is only needed if sysemu doesn't work >correctly and in a debug context. > >You must know that I don't want to make "cosmetic" work on sysemu >(except correcting the strace problem) because : I don't use UML (I make >this patch in a prospecting work), all my systems are powerpc based, >and he acknoweledged, that it would be ok, .... >> if not, via kernel-commandline-param, maybe this is even possible dynami= cally, from inside uml ? > >yes, from a /proc/sys toggle to set the internal "use_sysemu" variable to = 0. i think this would be useful to do better performance comparison and for de= termining the "real world" benefit of this patch (it`s like applying and releasing the br= ake) echo 1 >/proc/sysemu - now sysemu is ON benchmark your application/uml echo 0 >/proc/sysemu - now sysemu is OFF benchmark your application/uml again compare do you think this is useful ? i would have already done this "cosmetic work", but for sure i need some he= lp because i`m no good programmer (but i would like starting some kernelhacking :) i have read some docs how procfs programming is being done and it seems rea= sonable simple for me. so i want to hear your opinion first, before getting on your nerves with (r= eally dumb kernel- hackernewbie) questions for a feature, nobody wants to have :) roland ----- Original Message -----=20 From: "Laurent Vivier" To: "Jeff Dike" Cc: "roland" ; Sent: Wednesday, May 19, 2004 7:27 PM Subject: Re: [uml-devel] [PATCH] host context switch reduction Hi, as it is a plebiscite ;-), find attached the patch for UML 2.6.6 and measurements I made on my poor netserver. Laurent Le mar 18/05/2004 =E0 19:59, Jeff Dike a =E9crit : > On Tue, May 18, 2004 at 12:22:45AM +0200, roland wrote: > > the question is: > > is the "real world" performance benefit, uml get`s from this patch wort= h taking your time and is it implemented in a way, so that > > uml maintainers are happy with that ? > > The patch seems reasonable to me. I'd be happiest with Laurent pushing t= his > into mainline himself. > > > i cannot really estimate, what performance benefits your patch brings t= o uml in detail, but what i have seen so far, this seems > > quite worth doing the work. reducing context switches by 1/3 is a LOT,= imho - and reducing the execution time of the getpid-loop to > > nearly the half is quite impressive. > > Yeah, but no real workloads do while(1) getpid(); > > The kernel build improvement is obviously smaller, but still worth having. > > > are there any "con`s" that argue for that work _NOT_ being done ? > > No. But testing, and happy reports to the appropriate mailing lists would > help. > > Jeff ---------------------------------------------------------------------------= ----- > HP Netserver LH Pro bi-pro 200 MHz / 256 MB RAM > > NATIF: > > netserver:/usr/src# uname -a > Linux netserver 2.4.24-sysemu #4 SMP Tue Feb 17 16:43:11 CET 2004 i686 GN= U/Linux > > netserver:/usr/src# time ./getpid 1000000 > > real 0m1.763s > user 0m0.910s > sys 0m0.860s > > real 0m1.759s > user 0m0.900s > sys 0m0.870s > > real 0m1.759s > user 0m0.950s > sys 0m0.800s > > UML with sysemu: > > (none):~# uname -a > Linux (none) 2.6.6-1um #10 Wed May 19 12:54:37 CEST 2004 i686 unknown > > (none):/mnt/usr/src# time ./getpid 1000000 > > real 1m1.508s > user 0m7.960s > sys 0m53.450s > > real 1m1.881s > user 0m6.630s > sys 0m55.240s > > real 1m1.920s > user 0m6.580s > sys 0m55.340s > > UML w/o sysemu > > real 1m32.833s > user 0m7.610s > sys 1m25.130s > > real 1m32.921s > user 0m7.890s > sys 1m24.980s > > real 1m33.493s > user 0m8.010s > sys 1m24.960s > ------------------------------------------------------- This SF.Net email is sponsored by: Oracle 10g Get certified on the hottest thing ever to hit the market... Oracle 10g.=20 Take an Oracle 10g class now, and we'll give you the exam FREE. http://ads.osdn.com/?ad_id=3D3149&alloc_id=3D8166&op=3Dclick _______________________________________________ User-mode-linux-devel mailing list User-mode-linux-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-devel