Messages in this thread | | | Date | Thu, 03 May 2007 11:19:04 -0400 | From | Ting Yang <> | Subject | Re: [patch] CFS scheduler, -v8 |
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Srivatsa Vaddagiri wrote: > On Thu, May 03, 2007 at 10:50:15AM +0200, Ingo Molnar wrote: > >> - EEVDF concentrates on real-time (SCHED_RR-alike) workloads where they >> know the length of work units >> > > This is what I was thinking when I wrote earlier that EEVDF expects each > task will specify "length of each new request" > (http://lkml.org/lkml/2007/5/2/339). > This is not very true based on my understanding of EEVDF, please look at the email I just sent out to Ingo for explanation. > The other observation that I have of EEVDF is that it tries to be fair > in the virtual time scale (each client will get 'wi' real units in 1 > virtual unit), whereas sometimes fairness in real-time scale also > matters? > For ex: a multi-media app would call scheduler fair to it, it it recvs > atleast 1 ms cpu time every 10 *real* milleseconds (frame-time). A rogue > user (or workload) that does a fork bomb may skew this fairness for that > multi-media app in real-time scale under EEVDF? > First of all, CFS does not seems to address this issue to. This is a typical real-time or soft real-time question, that is not only the bandwidth of a task has to be fixed, i.e. 10% of cpu bandwidth (which proportional shared system, like CFS, EEVDF does not do), and the work need to satisfy a deadline. In both CFS, EEVDF, the scheduler have keep tweaking weights to give a fixed bandwidth to application. Authors of EEVDF claims this can be done, but never implemented :-(
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