On 14/01/2008, scott <[EMAIL PROTECTED]> wrote: > *** > Analogy: You're on a highway with a posted speed of 100 km/h. You want > to operate your car and your car only 25 km/h only on the 100 km/h > highway. > *** > > And for this happy privilege, you want to impose the attendant nuisance > (highway analogy), read overhead (o/s analogy), on all the other cars to > have to slow behind and pass around you.
This is a bad analogy because you can't do anything with the other 75 km/h. A better analogy would be a network connection that does not allow e.g. torrent traffic to exceed a particular fraction of the bandwidth. Or, if you want to find something to do with cars, a motorway with a separate lane for slow going vehicles (the slow moving vehicles will still be slow even though the other lanes might be empty). But I've understood from the other responses that this was not, even academically, an interesting problem, so I'll be quiet for a bit again. Thanks for all views, Andreas > > Generally, a time slice is a time slice. Regardless whether you get 1 > sec of every 10 sec or 100 ms of every 1 s, you're going to execute your > instructions at a rate of 100% of the cpu within your time slice > allocation. > > Now you can impose scheduler and threading overhead and discipline to > make your time slices very, very fine grained so that overall at a > system level it looks like 25% of a resource, but your rate of execution > within your context is going to be 100%. > > That said and for the cited examples, the workable answer that I know of > is virtual machines. Be it VMWare, XEN, solaris containers (zones), > freeBSD jails, qemu(*) or to a degree dragonflybsd (vkernel(*) -- > "system-in-a-box" running as a userland process), each has a means to > say that VM(1) gets 25% of the CPU resources and the vm-engine by > whatever implement will effectively do so. And you will see that seti, > for example, takes 100% of its VM(1) resource but only 25% of machine as > a whole, less the overhead. (*)Not used personally. > > And, yes, we're aware of the opines herein and about re VM. > > /S > > -----Original Message----- > From: Andreas Kahari <[EMAIL PROTECTED]> > To: Alexander Schrijver <[EMAIL PROTECTED]> > Cc: misc@openbsd.org > Subject: Re: Limiting CPU to a process or process group? > Date: Mon, 14 Jan 2008 14:27:33 +0000 > > > -- Andreas Kahari Somewhere in the general Cambridge area, UK
