Il 26/07/2013 11:08, Alex Bligh ha scritto:
>
>
> --On 26 July 2013 10:43:45 +0200 Stefan Hajnoczi <stefa...@gmail.com>
> wrote:
>
>> block.c and block/qed.c use vm_clock because block drivers should not do
>> guest I/O while the vm is stopped. This is especially true during live
>> migration where it's important to hand off the image file from the
>> source host to the destination host with good cache consistency. The
>> source host is not allowed to modify the image file anymore once the
>> destination host has resumed the guest.
>>
>> Block jobs use rt_clock because they aren't considered guest I/O.
>
> That's going to be 'interesting' if qemu-img uses a block driver that
> uses a timer, as I don't think the vm timer is running when qemu-img
> is running.
Yes, it is, see stubs/cpu-get-clock.c:
#include "qemu-common.h"
#include "qemu/timer.h"
int64_t cpu_get_clock(void)
{
return get_clock_realtime();
}
vm_clock becomes a synonym of rt_clock basically.
Paolo
