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Re: SMP does not work as expected - was: Re: [Xen-users] Checking for SMP usage in xen stable



Tom Brown schrieb:

this is just the normal P4/xeon hyperthreading isn't it? I don't know what
an IBM x335 is... so I'm just guessing that hyperthreading is available.

Yes, this is a Xeon that can do hyperthreading - but does SMP in Xen also work on hyperthreaded single cpus? I thought that hyperthreading is different from SMP.

If that works I can distribute CPU power in finer chunks on a dual processor hyperthreading machine.

I will test that.

Dirk

-Tom

On Mon, 7 Nov 2005, Dirk H. Schulz wrote:

Hi folks,

I looked somewhat deeper into the smp issue with Xen 2.0.7. I found that
smp is used even on machines with only one processor.

This is xm list on an IBM x335, a dual processor board with one processor:

   Name                  Id    Mem(MB)    CPU        State  Time(s)
Console
   Domain-0            0    123                0            r----
59931.7
   webdynown01    5    511                1            -b---
193.5    9605
   webstatown01    1    255                0            -b---
202.9    9601

I have configured CPU usage in the domU's config files. So two of one
CPUs are used, it seems.

This is xm list on a single processor machine:

   Name                  Id        Mem(MB)    CPU        State
Time(s)  Console
   Domain-0            0        123                0
r----   5567.2
   sync01                 2        95                   0
   -b---      1.8    9602

So it seems that on dual processor boards smp is somehow simulated if
there is just one processor present.

Is this a bug, or does it make sense somehow?

And now my original question comes up again: How can I - reliably -
verify that my xen kernel is running smp code?

Dirk

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