From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rik van Riel Subject: Re: Stolen and degraded time and schedulers Date: Wed, 14 Mar 2007 15:45:03 -0400 Message-ID: <45F850BF.5030702@redhat.com> References: <45F6D1D0.6080905@goop.org> <1173816769.22180.14.camel@localhost> <45F70A71.9090205@goop.org> <1173821224.1416.24.camel@dwalker1> <45F71EA5.2090203@goop.org> <45F74515.7010808@vmware.com> <45F77C27.8090604@goop.org> <45F846AB.6060200@vmware.com> <45F84E39.7030507@goop.org> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <45F84E39.7030507@goop.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.osdl.org Errors-To: virtualization-bounces@lists.osdl.org To: Jeremy Fitzhardinge Cc: dwalker@mvista.com, john stultz , paulus@au.ibm.com, Linux Kernel Mailing List , Con Kolivas , Chris Wright , Virtualization Mailing List , cpufreq@lists.linux.org.uk, schwidefsky@de.ibm.com, Thomas Gleixner , Ingo Molnar List-Id: virtualization@lists.linuxfoundation.org Jeremy Fitzhardinge wrote: >> How is time quantum getting stolen less important? Time quantum >> getting stolen results directly in more unnecessary context switches >> since we might steal the entire timeslice before the process even ran. > = > It doesn't matter why you didn't get the time; = Oh, but it does. System administrators can use steal time the same way they use iowait time: to spot bottlenecks on their systems. If you have a lot of iowait time, you know you want either faster IO or more memory. If you have a lot of steal time, you know you need to spread your virtual machines over more CPUs. Steal time allows you to see the difference between a busy system and an overloaded system. -- = Politics is the struggle between those who want to make their country the best in the world, and those who believe it already is. Each group calls the other unpatriotic.