On 02.02.17 06:14, David Gibson wrote: > From: Laurent Vivier <lviv...@redhat.com> > > This is a port to ppc of the i386 commit: > 00f4d64 kvmclock: clock should count only if vm is running > > We remove timebase_post_load function, and use the VM state > change handler to save and restore the guest_timebase (on stop > and continue). > > We keep timebase_pre_save to reduce the clock difference on > migration like in: > 6053a86 kvmclock: reduce kvmclock difference on migration > > Time base offset has originally been introduced by commit > 98a8b52 spapr: Add support for time base offset migration > > So while VM is paused, the time is stopped. This allows to have > the same result with date (based on Time Base Register) and > hwclock (based on "get-time-of-day" RTAS call). > > Moreover in TCG mode, the Time Base is always paused, so this > patch also adjust the behavior between TCG and KVM. > > VM state field "time_of_the_day_ns" is now useless but we keep > it to be able to migrate to older version of the machine. > > As vmstate_ppc_timebase structure (with timebase_pre_save() and > timebase_post_load() functions) was only used by vmstate_spapr, > we register the VM state change handler only in ppc_spapr_init(). > > Signed-off-by: Laurent Vivier <lviv...@redhat.com> > Signed-off-by: David Gibson <da...@gibson.dropbear.id.au>
Just a small heads-up: I've been debugging an OpenQA regression lately where our automated testing regressed with QEMU 2.9. With stock 2.9.1, I get a failure rate of "weird" effects (probably TB divergence between vcpus) of ~30%. With this patch reverted it's back to 0%. I *think* something here causes the TB offset of multiple threads (I'm running -smp 2,threads=2) to diverge. I'll keep debugging things tomorrow, but I'll be happy to see anyone else beat me to analyze what is going wrong ;). Alex
