From: Laurent V. <Lau...@wa...> - 2004-05-19 18:17:37
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Le mer 19/05/2004 à 20:01, roland a écrit : > 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 focus 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 ----- > From: "Laurent Vivier" <Lau...@wa...> > To: "Jeff Dike" <jd...@ad...> > Cc: "roland" <for...@gm...>; <use...@li...> > 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 à 19:59, Jeff Dike a écrit : > > 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 pushing this > > into mainline himself. > > > > > i cannot really estimate, what performance benefits your patch brings 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 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 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 > > > |