Re: Possible bugs and doubts about readjusting weights/slice-lengths from command prompt

[Ryan Harper <ryanh@us.ibm.com>]

* Amitayu Das <amitayudas@gmail.com> [2006-05-03 00:49]:

> 2. Say, I'm readjusting the slice lengths of running domains. While doing
> that, I make a mistake by having sum of the slice-lengths higher than
> period-length. In such cases, what does Xen actually do? I did not find
> sanity-checking code for such cases in xen/common/sched_sedf.c. Please let
> me know in case it's not there, why so or it's there, only I did not find
> it.

For time-driven domains, versus weighted domains in sched_sedf.c:1407

    /*
     * Sanity checking: note that disabling extra weight requires
     * that we set a non-zero slice.
     */
    if ( (cmd->u.sedf.period > PERIOD_MAX) ||
         (cmd->u.sedf.period < PERIOD_MIN) ||
         (cmd->u.sedf.slice  > cmd->u.sedf.period) ||
         (cmd->u.sedf.slice  < SLICE_MIN) )
        return -EINVAL;

period has bounds, slice cannot be greater than period, and slice cannot
be smaller than SLICE_MIN.  For any of these cases, the command will not
succeed.  You also might be interested in looking at
tools/xm-test/tests/sedf which has some simple sedf scheduler tests.


> 
> 3. I tried to modify/readjust the slice/period length (or weights) for
> domains from command prompt.  However, I  found out that  changes are
> immaterial after first attempt. That is, no matter what changes I made at
> second or third or fourth time, they are not actually taking place. Only,
> the changes made during the first attempt actually took place. Please let me
> know if this is a bug in the existing code or I should have done the things
> in a different manner.

Could you supply the xm sched-sedf commands and values you used?


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