Re: [Xen-devel] Queries on time quantum for domains

[Ryan Harper <ryanh@xxxxxxxxxx>]

* Arjun <cse.syslab@xxxxxxxxx> [2006-03-25 19:28]:
> Hi,
> 
> For both SEDF and BVT , what is the minimum and maximum time quantum for
> domains ? Can these be changed ? If so, from where ?

xen/common/sched_sedf.c has the following for min/max

#define PERIOD_MAX MILLISECS(10000) /* 10s  */
#define PERIOD_MIN (MICROSECS(10))  /* 10us */
#define SLICE_MIN (MICROSECS(5))    /*  5us */

You can display/modify period/slice/latency/extra/weight of the sedf
scheduler through xm:

# xm sched-sedf
Name                              ID Period(ms) Slice(ms) Lat(ms) Extra Weight
Domain-0                           0      20.0      15.0     0.0      1      0
# xm help sched-sedf
   sched-sedf [DOM] [OPTIONS]       Show|Set simple EDF parameters
              -p, --period          Relative deadline(ms).
              -s, --slice           Worst-case execution time(ms)
                                    (slice < period).
              -l, --latency         scaled period(ms) in case the domain
                                    is doing heavy I/O.
              -e, --extra           flag (0/1) which controls whether the
                                    domain can run in extra-time
              -w, --weight          mutually exclusive with period/slice and
                                    specifies another way of setting a domain's
                                    cpu period/slice.


> Also, is there any information on domain context-switch times  ?

There used to be a scheduler latency histogram that would track things
along those lines, but that has been removed from the tree for some
time.


-- 
Ryan Harper
Software Engineer; Linux Technology Center
IBM Corp., Austin, Tx
(512) 838-9253   T/L: 678-9253
ryanh@xxxxxxxxxx

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