On Tue, Jun 16, 2009 at 02:59:54PM -0400, Luke S Crawford wrote:
Bill McGonigle bill@bfccomputing.com writes:
On 06/15/2009 11:33 PM, Luke S Crawford wrote:
xm sched-credit -d 0 60000
Ah, ha! This appears to work. I didn't need to reserve a CPU for the dom0 (knock on wood). Much obliged, Luke.
I'm academically curious, though - I seem to have created a CPU deadlock of some sort, yet in 'xm top' none of the CPU's were pegged. I've got no reason to not give dom0 utmost priority - that makes perfect sense to me - but I'm surprised the Xen scheduler would allow me to get into this situation by default.
My understanding of this is entirely janitor-level, but I believe what you are seeing is that the dom0 has exhausted it's 'credits' and so if a DomU wants the CPU the dom0 gets kicked off the cpu, waits a timeslice (I think timeslices are on the order of tens of millaseconds... I've read 60ms, which is quite a long time in terms of sending a packet to a nearby storage box.) then gets back on the CPU.
afaik Xen credit scheduler assigns/changes credits every 30ms.
although CPU scheduling happens more often?
-- Pasi