On Thu, Oct 15, 2009 at 7:40 AM, Jeff Sturm <jeff.sturm@xxxxxxxxxx> wrote:
>> -----Original Message-----
>> What if the dom0 has no tasks once the domU is up and running?
>> eg: disable syslog, cron, etc on dom0
>> Can one assign all cores to the domU?
>> Or, must one core remain idle dedicated to handling dom0 processing?
> Dom0 can share a core, but it'll be timesliced if the dom0 has things to
> do. Which may not be good overall. I like to pin dom0 to one (or more)
> core, and leave everything else to domU.
> Whether this helps you or not depends on what the domU is doing. If
> your domU is compute-intensive, it may benefit from having access to all
> cores. But if it routinely does any block or network I/O, the dom0
> needs to get involved, since that's where the backend drivers usually
> run. And if dom0 has to wait for a CPU to become available, that may
> delay domU I/O.
This clarifies a lot, thanks Jeff.
I'm not intentionally being thick, but I want to cover all possibilities :-)
To extrapolate from that, if I wanted to avoid having dom0 competing
for a core, I would have to pass through any devices the domU needed
to access, or have hardware that supports sr-iov?
Just for the sake of argument, if I could eliminate all hardware
proxying requirements of the dom0, would a domU be able to hold on to
all the cores, or would the dom0 or hypervisor still periodically
"steal" a core?
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