>>> On 13.10.10 at 05:24, "Du, Hang" <hdu@xxxxxxxxxxxx> wrote:
> Sorry for my brief description in previous mail and missing
> is_initial_xendomain check. The kernel I submit this patch is
> linux-2.6.18-xen-3.4.2, I submit the patch again with in_initial-xendomain
> check.
Actually, I didn't expect you to blindly insert that check, but rather
either explain why only DomU-s need the changed behavior (as your
original description suggested), or refine the description of the
problem you're trying to solve.
> In this patch, we support the backward time changing sync to all domUs which
> configured to use "dependent wall clock".
> Currently, without the backward time syncing, when we change the time
> backward in Dom0, the time in DomU would be froze.
> And this cause some commands hang and don't executed until the time catch up
> with the domU time.
> For example:
> "rpm -q kernel-xen"
> "sleep 1"
> Monotonic time should be reset when sync up time from dom0 to domU to
> support domU backward time syncing.
I can see your point, however ...
> diff -urN a/arch/i386/kernel/time-xen.c b/arch/i386/kernel/time-xen.c
>
> --- a/arch/i386/kernel/time-xen.c 2010-10-11 10:41:06.000000000 +0800
> +++ b/arch/i386/kernel/time-xen.c 2010-10-11 10:43:32.000000000 +0800
> @@ -715,6 +715,8 @@
> }
>
> if (shadow_tv_version != HYPERVISOR_shared_info->wc_version) {
> + if (!is_initial_xendomain() && !independent_wallclock)
> + monotonic_reset();
> update_wallclock();
... you definitely need to call monotonic_reset() *after* the
update_wallclock() (or else another vCPU, preempted in
do_gettimeofday() between the end of the xtime read loop
and the acquiring of the monotonic lock, would be able to
overwrite monotonic.tv with values obtained before the wall
clock update - similar to the secondary problem addressed by
c/s 1021).
Further, blindly running a reset here doesn't seem nice in
the (general) case of the time getting updated forwards.
> schedule_clock_was_set_work = 1;
> }
You'll also want to address Dan's concerns, and you will want to
get your patch formatted so that it would actually apply (read:
no tab -> space conversion) if you expect it to be committed
by Keir at some point.
Jan
_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel
|
Home