* 0.11: SMP guests using one host CPU only?
@ 2009-10-20 9:03 Tomasz Chmielewski
2009-10-20 9:41 ` Avi Kivity
0 siblings, 1 reply; 10+ messages in thread
From: Tomasz Chmielewski @ 2009-10-20 9:03 UTC (permalink / raw)
To: kvm
On a 8 CPU host, I created a guest with 4 CPUs (-smp 4).
Unfortunately, the guest only uses one host CPU.
For example, running "cat /dev/urandom | gzip -9 >/dev/null &" several
times on this guest causes load on only one host CPU.
Is it expected?
The host is running 2.6.32-rc5 and qemu-kvm-0.11. I also tried 2.6.31.5
with qemu-kvm-0.11 with the same result.
I have another machine, running 2.6.24 kernel, where it works just fine
(running several CPU-intensive tasks on a guest result in several host
CPUs being loaded).
--
Tomasz Chmielewski
http://wpkg.org
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: 0.11: SMP guests using one host CPU only?
2009-10-20 9:03 0.11: SMP guests using one host CPU only? Tomasz Chmielewski
@ 2009-10-20 9:41 ` Avi Kivity
2009-10-20 10:17 ` Tomasz Chmielewski
0 siblings, 1 reply; 10+ messages in thread
From: Avi Kivity @ 2009-10-20 9:41 UTC (permalink / raw)
To: Tomasz Chmielewski; +Cc: kvm
On 10/20/2009 06:03 PM, Tomasz Chmielewski wrote:
> On a 8 CPU host, I created a guest with 4 CPUs (-smp 4).
>
> Unfortunately, the guest only uses one host CPU.
> For example, running "cat /dev/urandom | gzip -9 >/dev/null &" several
> times on this guest causes load on only one host CPU.
>
> Is it expected?
No. What does 'top -H' show?
--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: 0.11: SMP guests using one host CPU only?
2009-10-20 9:41 ` Avi Kivity
@ 2009-10-20 10:17 ` Tomasz Chmielewski
2009-10-20 13:16 ` Avi Kivity
0 siblings, 1 reply; 10+ messages in thread
From: Tomasz Chmielewski @ 2009-10-20 10:17 UTC (permalink / raw)
To: Avi Kivity; +Cc: kvm
Avi Kivity wrote:
> On 10/20/2009 06:03 PM, Tomasz Chmielewski wrote:
>> On a 8 CPU host, I created a guest with 4 CPUs (-smp 4).
>>
>> Unfortunately, the guest only uses one host CPU.
>> For example, running "cat /dev/urandom | gzip -9 >/dev/null &" several
>> times on this guest causes load on only one host CPU.
>>
>> Is it expected?
>
> No. What does 'top -H' show?
In the guest - 4 CPUs with ~100% usage each (when I press "1"), otherwise, in the task list, multiple "cat" processes taking most CPU time (as it reads from /dev/urandom).
In the host - qemu-system-x86 (one process/thread) taking ~100% CPU; when I press "1", I see only one CPU is used 100%, 7 other CPUs are more or less not used.
guest command line:
/usr/bin/qemu-system-x86_64 -m 1024 -drive file=/srv/kvm/images/lvs2,if=virtio,cache=writeback,index=0,boot=on -net nic,vlan=0,model=virtio,macaddr=F2:4A:51:41:B1:3F -net tap,vlan=0,script=/etc/qemu-ifup -localtime -smp 4
There are 5 other guests (1 CPU) started before this guest.
--
Tomasz Chmielewski
http://wpkg.org
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: 0.11: SMP guests using one host CPU only?
2009-10-20 10:17 ` Tomasz Chmielewski
@ 2009-10-20 13:16 ` Avi Kivity
2009-10-20 13:19 ` Tomasz Chmielewski
0 siblings, 1 reply; 10+ messages in thread
From: Avi Kivity @ 2009-10-20 13:16 UTC (permalink / raw)
To: Tomasz Chmielewski; +Cc: kvm
On 10/20/2009 07:17 PM, Tomasz Chmielewski wrote:
> Avi Kivity wrote:
>> On 10/20/2009 06:03 PM, Tomasz Chmielewski wrote:
>>> On a 8 CPU host, I created a guest with 4 CPUs (-smp 4).
>>>
>>> Unfortunately, the guest only uses one host CPU.
>>> For example, running "cat /dev/urandom | gzip -9 >/dev/null &"
>>> several times on this guest causes load on only one host CPU.
>>>
>>> Is it expected?
>>
>> No. What does 'top -H' show?
>
> In the guest - 4 CPUs with ~100% usage each (when I press "1"),
> otherwise, in the task list, multiple "cat" processes taking most CPU
> time (as it reads from /dev/urandom).
>
>
> In the host - qemu-system-x86 (one process/thread) taking ~100% CPU;
> when I press "1", I see only one CPU is used 100%, 7 other CPUs are
> more or less not used.
>
I meant, how many qemu threads are there, and how much cpu does each take?
--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: 0.11: SMP guests using one host CPU only?
2009-10-20 13:16 ` Avi Kivity
@ 2009-10-20 13:19 ` Tomasz Chmielewski
2009-10-20 13:21 ` Avi Kivity
0 siblings, 1 reply; 10+ messages in thread
From: Tomasz Chmielewski @ 2009-10-20 13:19 UTC (permalink / raw)
To: Avi Kivity; +Cc: kvm
Avi Kivity wrote:
> On 10/20/2009 07:17 PM, Tomasz Chmielewski wrote:
>> Avi Kivity wrote:
>>> On 10/20/2009 06:03 PM, Tomasz Chmielewski wrote:
>>>> On a 8 CPU host, I created a guest with 4 CPUs (-smp 4).
>>>>
>>>> Unfortunately, the guest only uses one host CPU.
>>>> For example, running "cat /dev/urandom | gzip -9 >/dev/null &"
>>>> several times on this guest causes load on only one host CPU.
>>>>
>>>> Is it expected?
>>>
>>> No. What does 'top -H' show?
>>
>> In the guest - 4 CPUs with ~100% usage each (when I press "1"),
>> otherwise, in the task list, multiple "cat" processes taking most CPU
>> time (as it reads from /dev/urandom).
>>
>>
>> In the host - qemu-system-x86 (one process/thread) taking ~100% CPU;
>> when I press "1", I see only one CPU is used 100%, 7 other CPUs are
>> more or less not used.
>>
>
> 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.
--
Tomasz Chmielewski
http://wpkg.org
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: 0.11: SMP guests using one host CPU only?
2009-10-20 13:19 ` Tomasz Chmielewski
@ 2009-10-20 13:21 ` Avi Kivity
2009-10-20 13:48 ` Tomasz Chmielewski
0 siblings, 1 reply; 10+ messages in thread
From: Avi Kivity @ 2009-10-20 13:21 UTC (permalink / raw)
To: Tomasz Chmielewski; +Cc: kvm
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.
What does 'ls /proc/$(pgrep qemu)/task' show?
--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: 0.11: SMP guests using one host CPU only?
2009-10-20 13:21 ` Avi Kivity
@ 2009-10-20 13:48 ` Tomasz Chmielewski
2009-10-22 7:05 ` Avi Kivity
0 siblings, 1 reply; 10+ messages in thread
From: Tomasz Chmielewski @ 2009-10-20 13:48 UTC (permalink / raw)
To: Avi Kivity; +Cc: kvm
Avi Kivity wrote:
> On 10/20/2009 10:19 PM, Tomasz Chmielewski wrote:
>>>
>>> I meant, how many qemu threads are there, and how much cpu does each
>>> take?
>>
>>
>> There is only one qemu thread for the 4-cpu guest.
>
> Not possible. Even a single-cpu guest has two threads.
"ps auxH" shuld show me all threads? I started it multiple times, and it shown 1 thread for the 4-CPU guest
(with no CPU intensive tasks running - could this be a reason?).
> What does 'ls /proc/$(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
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: 0.11: SMP guests using one host CPU only?
2009-10-20 13:48 ` Tomasz Chmielewski
@ 2009-10-22 7:05 ` Avi Kivity
2009-10-22 9:28 ` Tomasz Chmielewski
0 siblings, 1 reply; 10+ messages in thread
From: Avi Kivity @ 2009-10-22 7:05 UTC (permalink / raw)
To: Tomasz Chmielewski; +Cc: kvm
On 10/20/2009 04:48 PM, Tomasz Chmielewski wrote:
> 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?).
No. kvm implies 2+ threads.
>
>
>> 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?
>
Are you sure they're using kvm? Try 'info kvm' in the monitor. tcg
will only use on thread (more will be spawned for I/O, but will
eventually die).
--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: 0.11: SMP guests using one host CPU only?
2009-10-22 7:05 ` Avi Kivity
@ 2009-10-22 9:28 ` Tomasz Chmielewski
2009-10-22 10:51 ` Avi Kivity
0 siblings, 1 reply; 10+ messages in thread
From: Tomasz Chmielewski @ 2009-10-22 9:28 UTC (permalink / raw)
To: Avi Kivity; +Cc: kvm
Avi Kivity wrote:
>> Some 1-CPU guests have only one thread though?
>>
>
> Are you sure they're using kvm? Try 'info kvm' in the monitor. tcg
> will only use on thread (more will be spawned for I/O, but will
> eventually die).
Indeed, that was a good suggestion - they were not using KVM (support
not compiled in, and kvm didn't complain when starting).
IO and CPU speed was rather OK, so I didn't notice ;)
To sum up the thread: I guess qemu _without_ KVM will only use one CPU,
even when you assign more CPUs to the guest?
--
Tomasz Chmielewski
http://wpkg.org
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: 0.11: SMP guests using one host CPU only?
2009-10-22 9:28 ` Tomasz Chmielewski
@ 2009-10-22 10:51 ` Avi Kivity
0 siblings, 0 replies; 10+ messages in thread
From: Avi Kivity @ 2009-10-22 10:51 UTC (permalink / raw)
To: Tomasz Chmielewski; +Cc: kvm
On 10/22/2009 11:28 AM, Tomasz Chmielewski wrote:
> To sum up the thread: I guess qemu _without_ KVM will only use one
> CPU, even when you assign more CPUs to the guest?
>
Yes.
--
error compiling committee.c: too many arguments to function
^ permalink raw reply [flat|nested] 10+ messages in thread
end of thread, other threads:[~2009-10-22 10:51 UTC | newest]
Thread overview: 10+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2009-10-20 9:03 0.11: SMP guests using one host CPU only? Tomasz Chmielewski
2009-10-20 9:41 ` Avi Kivity
2009-10-20 10:17 ` Tomasz Chmielewski
2009-10-20 13:16 ` Avi Kivity
2009-10-20 13:19 ` Tomasz Chmielewski
2009-10-20 13:21 ` Avi Kivity
2009-10-20 13:48 ` Tomasz Chmielewski
2009-10-22 7:05 ` Avi Kivity
2009-10-22 9:28 ` Tomasz Chmielewski
2009-10-22 10:51 ` Avi Kivity
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