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 1BQdHP-0006Np-FH for user-mode-linux-devel@lists.sourceforge.net; Wed, 19 May 2004 19:27:31 -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 1BQdHO-0006Me-F3 for user-mode-linux-devel@lists.sourceforge.net; Wed, 19 May 2004 19:27:30 -0700 Message-ID: <05a101c43e12$fc797c10$2000000a@schlepptopp> From: "roland" 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 04:34:32 +0200 Content-Transfer-Encoding: quoted-printable To: Laurent Vivier Cc: Jeff Dike , user-mode-linux-devel@lists.sourceforge.net, blaisorblade_spam@yahoo.it ohh.. that mail was still open in the background....waiting to be send :) i recognized that blaisorblades skas-patch doesn`t seem to activate skas in .config by default, so my uml`s accidently ran in TT Mode. Recompiled the HOST and the effect i mentioned doesn`t happen with skas. btw: the getpid-loop is more than THREE TIMES faster with skas. i hope skas will do it`s way into the mainstream-kernel, so TT is obsolete = soon. skas should be a MUST for uml :) jeff - can we expect this happening soon, or doesn`t that happen before ska= s4 ? suse-distro has skas in their kernels - in 9.0 and also in 9.1 - so i would= think, skas is ready for the kernel.....but....linus decides :) so - that`s enough mails. sorry for that "spamming" today. i promise to reduce my output :) regards roland ----- Original Message -----=20 From: "roland" To: "Laurent Vivier" Cc: "Jeff Dike" ; Sent: Thursday, May 20, 2004 3:01 AM Subject: Re: [uml-devel] [PATCH] host context switch reduction > while testing laurents patch, > i have made the following interesting observation: > > 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. :) > > ok - i would say: > yes - the system is heavily stressed - a busy uml makes the other one beh= ave > sluggish, too .....but..... > > why don`t i see any sluggish behaviour on the HOST itself ? > > want to reproduce? > > compile this little program and transfer it to your uml-root_fs`s > -------------------------- > int main(void) > { > int i; > for(i=3D0;i<1000000;i++) > getpid(); > } > -------------------------- > > - let it run in one uml and the other uml(s) get sluggish - typing into t= he window and > issuing commands gives very slow response > - on the HOST there is no noticeable performance loss - typing,echoing, l= s -la, df -kl, > ... all seems normal and "feels" quite good. > - stop the getpid program and start another cpu/io hog (e.g. "while true;= do find /;done) > inside one uml and compare that behaviour. other uml`s behave quite ok = - the host, too. > no sluggish behaviour. > > maybe this behaviour is quite normal (ok - a getpid-loop is a worst case = scenario) - but > my system knowledge isn`t good enough, to explain , what`s going on here = in detail. > > is it, because the processing overhead of an uml is so high - so typing a= char or issuing a > command "costs" so much more in an uml, so that we just can "see" the per= formance drop here, > and not on the host ? > > regards > roland > > > > ----- Original Message -----=20 > From: "Laurent Vivier" > To: "roland" > Cc: "Jeff Dike" ; > Sent: Wednesday, May 19, 2004 8:17 PM > Subject: Re: [uml-devel] [PATCH] host context switch reduction > > > Le mer 19/05/2004 =E0 20:01, roland a =E9crit : > > Hi Laurent ! > > Great! > > Thanks a lot for your work :) > > > > but i have a question: > > > > old mail from jeff: > > >The patches below are from Laurent Vivier who didn't make them public.= They > > >add a new feature to ptrace on the host which cuts down on the number = of > > >context switches needed for a UML system call, plus makes UML use it > > > > so - if your patch adds a new feature for ptrace on the HOST - shouldn`= t we need TWO patches for 2.6 ? > > One patch for uml and one patch for the host ? > > > > this one seems for uml only. > > some of us already run uml 2.6(.x) on a 2.6.(.x) host and put their foc= us on the "new kernel" (me too). > > OK, as I didn't find skas patch for 2.6 I thought it didn't exist... > anyway I tried to port the 2.4 host sysemu patch to 2.6, find it > attached. I never tested it, or compiled it ! I have no system with 2.6 > kernel, and the only I386 system I have is very, very, very noisy... > it's a good system only when it is switched off ;-) ! > > > regards > > roland > > > > ps: > > since this would be the 2nd patch for the HOST (besides skas), would it= make sense, to merge "skas" and "sysemu" into one common > > HOST-patch (if it has been tested and approved stable) ? > > > > YES, I think... but Jeff is the boss ;-) > > > > > > > ----- 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 = worth 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 pushi= ng this > > > into mainline himself. > > > > > > > i cannot really estimate, what performance benefits your patch brin= gs to 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 ha= ving. > > > > > > > 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 i68= 6 GNU/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... 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