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Re: [Xen-users] SEDF and latency parameter

Timo Benk wrote:

can someone explain or point me to some doku where the latency parameter
for the SEDF Parameter is explained?

Hi Timo,

Suse 10. is accompanied by some interesting xen doku stuff. See /usr/share/doc/xen. Here is the supplied documentation on sedf which contains info on the latency parameter which will hopefully helpful to you.

If - and how - it works please let us know (have no experience with this so far)

sEDF scheduler
  Stephan.Diestelhorst@{cl.cam.ac.uk, inf.tu-dresden.de}
 This scheduler provides weighted CPU sharing in an intuitive way and
 uses realtime-algorithms to ensure time guarantees.

  -add "sched=sedf" on Xen's boot command-line
  -create domains as usual
-use "xm sched-sedf <dom-id> <period> <slice> <latency-hint> <extra> <weight>"
     -period/slice are the normal EDF scheduling parameters in nanosecs
-latency-hint is the scaled period in case the domain is doing heavy I/O
        (unused by the currently compiled version)
     -extra is a flag (0/1), which controls whether the domain can run in
     -weight is mutually exclusive with period/slice and specifies another
      way of setting a domains cpu slice

normal EDF (20ms/5ms):
 xm sched-sedf <dom-id> 20000000 5000000 0 0 0

best-effort domains (i.e. non-realtime):
 xm sched-sedf <dom-id> 20000000 0 0 1 0

normal EDF (20ms/5ms) + share of extra-time:
 xm sched-sedf <dom-id> 20000000 5000000 0 1 0

4 domains with weights 2:3:4:2
 xm sched-sedf <d1> 0 0 0 0 2
 xm sched-sedf <d2> 0 0 0 0 3
 xm sched-sedf <d3> 0 0 0 0 4
 xm sched-sedf <d4> 0 0 0 0 2

1 fully-specified (10ms/3ms) domain, 3 other domains share
available rest in 2:7:3 ratio:
 xm sched-sedf <d1> 10000000 3000000 0 0 0
 xm sched-sedf <d2> 0 0 0 0 2
 xm sched-sedf <d3> 0 0 0 0 7
 xm sched-sedf <d4> 0 0 0 0 3


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