* 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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