Re: slow guest performance with build load, looking for ideas

[Avi Kivity <avi@redhat.com>]

On 07/09/2009 09:01 PM, Erik Jacobson wrote:
>
>> Please drop -usbdevice tablet and set the host I/O scheduler to
>> deadline.  Add cache=none to the -drive options.
>>      
>
> yes, these changes make a difference.
>
>
> Before starting qemu-kvm, I did this to change the IO scheduler:
> BEFORE:
> # for f in /sys/block/sd*/queue/scheduler; do cat $f; done
> noop anticipatory deadline [cfq]
> noop anticipatory deadline [cfq]
>
> SET:
> # for f in /sys/block/sd*/queue/scheduler; do echo "deadline">  $f; done
>
> CONFIRM:
> # for f in /sys/block/sd*/queue/scheduler; do cat $f; done
> noop anticipatory [deadline] cfq
> noop anticipatory [deadline] cfq
>
>
> qemu command line.  Note that usbtablet is off and cache=none is used in
> drive options:
>
> /usr/bin/qemu-kvm -M pc -m 4096 -smp 8 -name f11-test -uuid b7b4b7e4-9c07-22aa-0c95-d5c8a24176c5 -monitor pty -pidfile /var/run/libvirt/qemu//f11-test.pid -drive file=/var/lib/libvirt/images/f11-test.img,if=virtio,index=0,boot=on,cache=none -drive file=/dev/sdb,if=virtio,index=1,cache=none -drive file=/var/lib/libvirt/images/test.img,if=virtio,index=2,cache=none -net nic,macaddr=54:52:00:46:48:0e,model=virtio -net user -serial pty -parallel none -usb -vnc cct201:1 -soundhw es1370 -redir tcp:5555::22
>
>
> # rotation enabled this way in the guest, once the guest was started:
> for f in /sys/block/vd*/queue/rotational; do echo 1>  $f; done
>
> Test runs after make clean...
> time (make -j12&&   make -j12 modules)
>
> real	10m25.585s
> user	26m36.450s
> sys	8m14.776s
>
> 2nd trial (make clean followed by the same test again.
> real	9m21.626s
> user	26m42.144s
> sys	8m14.532s
>
>    

That's a scaling of 3.7, still pretty far from the host and even farther 
than my results.

Is the numa factor of this machine larger than usual?

-- 
error compiling committee.c: too many arguments to function