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 [email protected]
Boulder, CO 80301 http://www.nwra.com
