Re: [Xen-devel] bug # 477

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 30 Mar 2006, at 09:57, Keir Fraser wrote:

> I bet this behaviour is due to two problems.
>  1. The daemon is probably looking for console data before it clears 
> the event fd. So if no data available then the fd doesn't get cleared 
> and the select() doesn't block next time round.
>  2. I think we still have a stupid scheduler default for domain0 where 
> it gets all the CPU it wants and can starve out domUs. So once 
> xenconsoled starts spinning, that's it for you if the domain it's 
> spinning on is supposed to run on the same CPU.
> I'll look at fixing both of these.
Actually the first issue was a bit different to what I describe above, 
but it's now fixed in changeset 9475.
The second issue is a bug in the SEDF scheduler I think. It's supposed 
to be guaranteed 75% of the CPU, plus share the remaining 25% with 
other domains in a 'fair' way. But it seems that domains that are given 
a real-time guarantee plus extratime basically get strict preference 
when allocating extratime. I haven't looked at fixing this -- it would 
be great is someone else wants to take a look.
 -- Keir


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