On 03/03/2011 02:25, "James Harper" <james.harper@xxxxxxxxxxxxxxxx> wrote:
> A user of GPLPV (see thread "blue screen in windows balloon driver") is
> getting a bug check in Windows under extremely high memory usage and
> swapfile thrashing tests across multiple DomU's. Responses to my query
> on the ntdev mailing list say that this would happen if an IO request is
> not completed after 70 seconds during high memory/pagefile pressure,
> which is what is happening.
>
> It appears that Dom0 is not servicing vbd requests from DomU's fairly so
> one or two end up getting stalled while the others are mostly okay. How
> are vbd requests supposed to be serviced? Is there potential for one to
> be overlooked for a long period of time? Is there some settings that
> could be changed to avoid this happening?
Dom0 does round-robin scanning of pending event channels these days, which
helps fairness a fair bit. When a pending event is found, the corresponding
blkfront has a batch of requests pulled down and submitted into Linux's
block subsystem at which point we have no more control over scheduling (it
could generally be configured though -- Linux has an admin mechanism for
that).
 -- Keir
> Thanks
>
> James
>
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