Re: [Qemu-devel] [PATCH v2 0/4] RTC: New logic to emulate RTC

[Zhang, Yang Z]

> -----Original Message-----
> From: Paolo Bonzini [mailto:address@hidden On Behalf Of Paolo
> Bonzini
> Sent: Monday, February 20, 2012 3:41 PM
> 
> On 02/20/2012 01:24 AM, Zhang, Yang Z wrote:
> > Changes in v2:
> > Add UIP check logic.
> > Add logic that next second tick will occur in exactly 500ms later
> > after setting the clock
> >
> > Current RTC emulation uses periodic timer(2 timers per second) to update RTC
> clock. And it will stop CPU staying at deep C-state for long period. Our 
> experience
> shows the Pkg C6 residency reduced 6% when running 64 idle guest.
> > The following patch stop the two periodic timer and only updating RTC clock
> when guest try to read it.
> >
> > ---
> > Yang Zhang (4):
> >     RTC: Update the RTC clock only when reading it
> >     RTC: Add RTC update-ended interrupt support
> >     RTC: Add alarm support
> >     RTC: Add UIP(update in progress) check logic
> >
> >     hw/mc146818rtc.c |  447
> +++++++++++++++++++++++++++++++++++++-----------------
> >     1 files changed, 308 insertions(+), 139 deletions(-)
> >
> > best regards
> > yang
> >
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> 
> Thanks, this looks much better!  I'll run it through some tests.
> 
> We also should try to keep migration working from older versions using the
> load_old callback.
Sure, I missed it. Will add it to the version 3. 
Any other comments?

best regards
yang