[Libvir] Add scheduler patch?

Atsushi SAKAI sakaia at jp.fujitsu.com
Tue Jun 5 10:42:31 UTC 2007

Hi, Daniel

Thank you for reviewing.

About xenHypervisorSetSchedulerParameters() in case of credit scheduler.
I just set not changed parameter at first.
I guess no problem on this.
Any problem?

+            /* credit scheduler parameters 
+             * following values do not change the parameters 
+             */
+            op_dom.u.getschedinfo.u.credit.weight = 0;
+            op_dom.u.getschedinfo.u.credit.cap    = (uint16_t)~0U;

Atsushi SAKAI

Daniel Veillard <veillard at redhat.com> wrote:

> On Tue, Jun 05, 2007 at 11:23:43AM +0900, Atsushi SAKAI wrote:
> > Hi, Daniel
> > 
> > I confirmed to work Xen3.1.0 only.
> > And not run on Xen3.0.4.(I guess domctl hypercall problem.)
> > And not tested yet for Xen3.0.3.
> > 
> > This is the reason I limit to work this command.
>  Okay, I will double check on a 3.0.3 box.
> I also surprized in xenHypervisorSetSchedulerParameters(), in the
> XEN_SCHEDULER_CREDIT, you loop on the params to extract the values for
> weight and cap, but you never error:
>   - if you can't interpret one of the parameters
>   - if no parameters is actually found.
> The memset at the beginning set to 0 those 2 values. I wonder what the
> result of calling the hypercall with (0, 0) means (or if one of the values
> is 0), I'm afraid it could actually hang the domain, without any error being
> raise if there is a missing parameter. I could see 2 ways to fix this:
>    - either prepopulate the weight and cap values by an earlier hypercall
>    - or fail if while going through the loop we don't get the 2 values.
> The second option seems nicer. The current error handling there is not
> okay, especially since there is no indication in the documentation on 
> what the parameters needed might be (i.e. basically the only way to get
> this to work for someone else is by trial and no error is ever raised,
> so that really need to be fixed).
> Daniel
> -- 
> Red Hat Virtualization group http://redhat.com/virtualization/
> Daniel Veillard      | virtualization library  http://libvirt.org/
> veillard at redhat.com  | libxml GNOME XML XSLT toolkit  http://xmlsoft.org/
> http://veillard.com/ | Rpmfind RPM search engine  http://rpmfind.net/

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