[Qemu-devel] smp: linux guest only sees 1 CPU when not using KVM

[Qemu-devel] smp: linux guest only sees 1 CPU when not using KVM

[Lluís]

Well, thre's nothing more to add than the contents in the subject.

I tried booting up with -smp 2, and /proc/cpuinfo on the linux guest
only return one CPU, while booting with "-smp 2 -enable-kvm" shows 2
CPUs.

Lluis

-- 
 "And it's much the same thing with knowledge, for whenever you learn
 something new, the whole world becomes that much richer."
 -- The Princess of Pure Reason, as told by Norton Juster in The Phantom
 Tollbooth

Re: [Qemu-devel] smp: linux guest only sees 1 CPU when not using KVM

[Lennart Sorensen]

On Mon, Nov 08, 2010 at 10:57:19PM +0100, Lluís wrote:
> Well, thre's nothing more to add than the contents in the subject.
> 
> I tried booting up with -smp 2, and /proc/cpuinfo on the linux guest
> only return one CPU, while booting with "-smp 2 -enable-kvm" shows 2
> CPUs.

I was under the impression qemu didn't emulate SMP.  KVM on the other
hand does support running on real SMP hardware.  It doesn't have to
emulate SMP after all.

-- 
Len Sorensen

Re: [Qemu-devel] smp: linux guest only sees 1 CPU when not using KVM

[Lluís]

Lennart Sorensen writes:

> On Mon, Nov 08, 2010 at 10:57:19PM +0100, Lluís wrote:
>> Well, thre's nothing more to add than the contents in the subject.
>> 
>> I tried booting up with -smp 2, and /proc/cpuinfo on the linux guest
>> only return one CPU, while booting with "-smp 2 -enable-kvm" shows 2
>> CPUs.

> I was under the impression qemu didn't emulate SMP.  KVM on the other
> hand does support running on real SMP hardware.  It doesn't have to
> emulate SMP after all.

Well, I thought it did when I saw the "-smp" option, and it does in fact
create multiple CPUState objects, as if the "extra" cpus where
unplugged.

In fact, cpus.c:cpu_exec_all does indeed loop through all the CPUState
objects, calling qemu_cpu_exec on each.

Lluis

-- 
 "And it's much the same thing with knowledge, for whenever you learn
 something new, the whole world becomes that much richer."
 -- The Princess of Pure Reason, as told by Norton Juster in The Phantom
 Tollbooth

Re: [Qemu-devel] smp: linux guest only sees 1 CPU when not using KVM

[Gleb Natapov]

On Mon, Nov 08, 2010 at 11:30:52PM +0100, Lluís wrote:
> Lennart Sorensen writes:
> 
> > On Mon, Nov 08, 2010 at 10:57:19PM +0100, Lluís wrote:
> >> Well, thre's nothing more to add than the contents in the subject.
> >> 
> >> I tried booting up with -smp 2, and /proc/cpuinfo on the linux guest
> >> only return one CPU, while booting with "-smp 2 -enable-kvm" shows 2
> >> CPUs.
> 
> > I was under the impression qemu didn't emulate SMP.  KVM on the other
> > hand does support running on real SMP hardware.  It doesn't have to
> > emulate SMP after all.
> 
> Well, I thought it did when I saw the "-smp" option, and it does in fact
> create multiple CPUState objects, as if the "extra" cpus where
> unplugged.
> 
> In fact, cpus.c:cpu_exec_all does indeed loop through all the CPUState
> objects, calling qemu_cpu_exec on each.
> 
Yes. Qemu should emulate smp fine. What "info cpus" in monitor shows?
Anything interesting in dmesg?

--
			Gleb.

Re: [Qemu-devel] smp: linux guest only sees 1 CPU when not using KVM

[Lluís]

Gleb Natapov writes:

> Yes. Qemu should emulate smp fine. What "info cpus" in monitor shows?
> Anything interesting in dmesg?

Hmpf. I tried again with a clean version, so either I was too sleepy
yesterday or my changes unexpectedly broke SMP.

As I still have to resolve some conflicts, I'll try later and reply in
case the problem persists.

In any case sorry for the inconvenience.

Lluis

-- 
 "And it's much the same thing with knowledge, for whenever you learn
 something new, the whole world becomes that much richer."
 -- The Princess of Pure Reason, as told by Norton Juster in The Phantom
 Tollbooth