| |
|
 |
|
 |
|
|
|
| |
|
|
xen-devel
Re: [Xen-devel] Scheduling of I/O domains
> It seems to me that this problem doesn't have anything to do with the
> choice of scheduling policy or parameters; It is about when the
> scheduler is called. It appears as though the xen cpu scheduler
> currently only runs when the hardware timer ticks. It does not run when
> an external interrupt happens. So there is a large latency introduced to
> I/O interrupts, and this limits I/O performance. Changing the scheduler
> algorithm won't help this.
>
> The only way to avoid this is to immediately dispatch the I/O domain
> responsible for a given I/O interrupt as soon as that interrupt occurs.
> This means giving I/O domains with pending interrupts scheduling
> priority over any "regular" domains. Just as in a "normal" operating
> system, interrupt service routines must complete before any user
> processes are executed. Otherwise, latencies are introduced that kill
> I/O performance.
When an event is queued for a domain we call a generic wakeup
function. A good deal more of that function ought to be
scheduler-specific, and should do something smarter than our current
default (which is to force a reschedule only if the CPU is idling).
However, fixing this shouldn't be that hard -- we should have saner
scheduling in the next few weeks.
-- Keir
-------------------------------------------------------
This SF.Net email is sponsored by BEA Weblogic Workshop
FREE Java Enterprise J2EE developer tools!
Get your free copy of BEA WebLogic Workshop 8.1 today.
http://ads.osdn.com/?ad_id=4721&alloc_id=10040&op=click
_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxxx
https://lists.sourceforge.net/lists/listinfo/xen-devel
|
|
|
| |
|
Home