Re: [Xen-users] SEDF and latency parameter

[Andrej Radonic <andrej.radonic@xxxxxxxx>]

Timo Benk wrote:
> Hi,
>
> can someone explain or point me to some doku where the latency parameter
> for the SEDF Parameter is explained?
>
> Greetings,
> -timo
>   
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)
<quote>
sEDF scheduler
--------------
Author:
  Stephan.Diestelhorst@{cl.cam.ac.uk, inf.tu-dresden.de}
 
Overview:
 This scheduler provides weighted CPU sharing in an intuitive way and
 uses realtime-algorithms to ensure time guarantees.

Usage:
  -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>"
   Where:
     -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
      extra-time
     -weight is mutually exclusive with period/slice and specifies another
      way of setting a domains cpu slice

Examples:
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
</quote>

Cheers,
Andrej

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