On 07/17/2012 09:28 PM, Vladimir Mosgalin wrote: > Hi Orion Poplawski! > > On 2012.07.17 at 16:46:19 -0600, Orion Poplawski wrote next: > >>> That depends heavily on what version of Fedora they are (particularly Rawhide >>> instances), and what services they are running. >> >> Well, I have a Fedora 17 instance running now with nothing but >> kernel processes and the qemu-kvm process still shows using 7-8% >> cpu. > > > Run "vmstat 1 10" on both guests and compare output; look for > differences in amount of context switches, CPU system usage and such. > F17 does seem to show periodic bursts of interrupts. In one minute, F17 shows: 182 virtio0-input 17 virtio1-requests 1617 Local timer interrupts 583 Rescheduling interrupts 663 Function call interrupts 17 TLB shootdowns SL6: 179 virtio0-input 17 virtio1-requests 849 Local timer interrupts 0 Rescheduling interrupts 0 Function call interrupts 0 TLB shootdown So perhaps that's a clue. > Also running powertop and comparing wakeups/sec and general output on > guests might give some hint. > > Unfortunately we have 2.0 on F17 and 1.11 on SL6 so the out put is a bit different. But on SL6: Top causes for wakeups: 25.4% ( 4.3) <kernel core> : hrtimer_start (tick_sched_timer) 13.6% ( 2.3) <interrupt> : virtio0-input 13.0% ( 2.2) mysqld : hrtimer_start_range_ns (hrtimer_wakeup) 11.8% ( 2.0) rpc.gssd : hrtimer_start_range_ns (hrtimer_wakeup) 11.8% ( 2.0) <kernel core> : clocksource_watchdog (clocksource_watchdog) 8.9% ( 1.5) events/0 : queue_delayed_work (delayed_work_timer_fn) 5.9% ( 1.0) httpd : hrtimer_start_range_ns (hrtimer_wakeup) 4.7% ( 0.8) <kernel core> : hrtimer_start_range_ns (tick_sched_timer) 1.2% ( 0.2) <kernel core> : bdi_arm_supers_timer (sync_supers_timer_fn) 0.6% ( 0.1) <kernel core> : start_bandwidth_timer (sched_rt_period_timer) 0.6% ( 0.1) httpd : sys_epoll_wait (process_timeout) 0.6% ( 0.1) hald : hrtimer_start_range_ns (hrtimer_wakeup) 0.6% ( 0.1) <kernel core> : neigh_timer_handler (neigh_timer_handler) 0.6% ( 0.1) flush-252:0 : schedule_timeout_interruptible (process_timeout) 0.6% ( 0.1) bdi-default : bdi_forker_task (process_timeout) Not much on F17 either: Summary: 22.5 wakeups/second, 0.0 GPU ops/second, 0.0 VFS ops/sec and 0.4% CPU use Usage Events/s Category Description 87.4 µs/s 6.9 Interrupt [1] timer(softirq) 165.6 µs/s 3.7 Timer rh_timer_func 57.0 µs/s 2.7 Interrupt [3] net_rx(softirq) 58.3 µs/s 1.9 Process /usr/sbin/rpc.gssd 46.7 µs/s 1.4 Timer clocksource_watchdog 2.1 µs/s 1.0 kWork sync_cmos_clock 270.1 µs/s 0.4 Process packagekitd 696.5 µs/s 0.20 Process powertop 122.4 µs/s 0.3 Process gdbus 3.3 µs/s 0.3 Process [fsnotify_mark] 568.5 µs/s 0.10 Process /usr/lib/systemd/systemd But there are bursts of swapper: Summary: 16.5 wakeups/second, 0.0 GPU ops/second, 0.0 VFS ops/sec and 20.5% CPU use Usage Events/s Category Description 144.9 ms/s 0.00 Process swapper/3 58.1 ms/s 0.00 Process swapper/0 188.5 µs/s 3.8 Timer rh_timer_func But the qemu-kvm cpu % is fairly steady on the host. -- Orion Poplawski Technical Manager 303-415-9701 x222 NWRA, Boulder Office FAX: 303-415-9702 3380 Mitchell Lane [log in to unmask] Boulder, CO 80301 http://www.nwra.com