Re: 0.11: SMP guests using one host CPU only?

[Tomasz Chmielewski <mangoo@wpkg.org>]

Avi Kivity wrote:
> On 10/20/2009 10:19 PM, Tomasz Chmielewski wrote:
>>>
>>> I meant, how many qemu threads are there, and how much cpu does each 
>>> take?
>>
>>
>> There is only one qemu thread for the 4-cpu guest.
> 
> Not possible.  Even a single-cpu guest has two threads.

"ps auxH" shuld show me all threads? I started it multiple times, and it shown 1 thread for the 4-CPU guest
(with no CPU intensive tasks running - could this be a reason?).

 
> What does 'ls /proc/$(pgrep qemu)/task' show?

Running several CPU-intensive processes on this guest uses only one CPU on the host.

Both "ps auxH" and /proc confirm that this guest has 4-5 threads when I run several CPU-intensive apps.

Only one thread for this guest uses 100% CPU time; other threads use ~0%.

If I don't run any CPU-intensive tasks on this guests, it only runs one thread (unless I misinterpret something here).


Some 1-CPU guests have only one thread though?


# QEMU_TASKS=$(pgrep qemu)

# for QEMU_TASK in $QEMU_TASKS; do cat /proc/$QEMU_TASK/cmdline ; echo ; ls /proc/$QEMU_TASK/task ; echo ; done
/usr/bin/qemu-system-x86_64-m1024-drivefile=/srv/kvm/images/lvs2,if=virtio,cache=writeback,index=0,boot=on-netnic,vlan=0,model=virtio,macaddr=F2:4A:51:41:B1:3F-nettap,vlan=0,script=/etc/qemu-ifup-localtime-smp4
17687/  19018/  19020/  19069/

/usr/bin/qemu-system-x86_64-m1024-drivefile=/srv/kvm/images/gluster1a,if=virtio,cache=writeback,index=0,boot=on-netnic,vlan=0,model=virtio,macaddr=F2:4A:51:41:B1:3A-nettap,vlan=0,script=/etc/qemu-ifup-localtime
19220/  24857/

/usr/bin/qemu-system-x86_64-m1024-drivefile=/srv/kvm/images/gluster2a,if=virtio,cache=writeback,index=0,boot=on-netnic,vlan=0,model=virtio,macaddr=F2:4A:51:41:B1:3B-nettap,vlan=0,script=/etc/qemu-ifup-localtime
19252/  24896/

/usr/bin/qemu-system-x86_64-m1024-drivefile=/srv/kvm/images/gluster3a,if=virtio,cache=writeback,index=0,boot=on-netnic,vlan=0,model=virtio,macaddr=F2:4A:51:41:B1:3C-nettap,vlan=0,script=/etc/qemu-ifup-localtime
19258/  24934/

/usr/bin/qemu-system-x86_64-m1024-drivefile=/srv/kvm/images/gluster4a,if=virtio,cache=writeback,index=0,boot=on-netnic,vlan=0,model=virtio,macaddr=F2:4A:51:41:B1:3D-nettap,vlan=0,script=/etc/qemu-ifup-localtime
25878/

/usr/bin/qemu-system-x86_64-m1024-drivefile=/srv/kvm/images/lvs1,if=virtio,cache=writeback,index=0,boot=on-netnic,vlan=0,model=virtio,macaddr=F2:4A:51:41:B1:3E-nettap,vlan=0,script=/etc/qemu-ifup-localtime
25920/



No CPU-intensive apps:

/usr/bin/qemu-system-x86_64-m1024-drivefile=/srv/kvm/images/lvs2,if=virtio,cache=writeback,index=0,boot=on-netnic,vlan=0,model=virtio,macaddr=F2:4A:51:41:B1:3F-nettap,vlan=0,script=/etc/qemu-ifup-localtime-smp4
17687/



-- 
Tomasz Chmielewski
http://wpkg.org