Re: [Xen-devel] [PATCH 0/5] RTC: New logic to emulate RTC

["Zhang, Yang Z" <yang.z.zhang@xxxxxxxxx>]

Umm....we use internal mirror and the service is broken for two days. So I 
cannot pull the latest update and thought those patches are not in. 
I just got the message that our server is broken, then check it in xen.org and 
found those patches already are applied.
Also the typo is corrected by keir. Thanks.
Sorry for the redundant mais.

best regards
yang

> -----Original Message-----
> From: xen-devel-bounces@xxxxxxxxxxxxx
> [mailto:xen-devel-bounces@xxxxxxxxxxxxx] On Behalf Of Zhang, Yang Z
> Sent: Thursday, March 08, 2012 9:14 AM
> To: xen-devel@xxxxxxxxxxxxxxxxxxx
> Subject: Re: [Xen-devel] [PATCH 0/5] RTC: New logic to emulate RTC
> 
> Sorry, due to the bad outlook auto format. The patch format is wrong.:(
> Will resend it under linux.
> 
> best regards
> yang
> 
> 
> > -----Original Message-----
> > From: Zhang, Yang Z
> > Sent: Thursday, March 08, 2012 8:42 AM
> > To: xen-devel@xxxxxxxxxxxxxxxxxxx
> > Subject: [PATCH 0/5] RTC: New logic to emulate RTC
> >
> > RESEND:
> > Correct a typo in comments.
> >
> > Current RTC emulation uses periodic timer(2 per second) to emulate RTC clock
> > update. And it will stop CPU staying at deep C-state for long period even 
> > when
> > guest is idle. Our experience shows the Pkg C6 residency reduced 6% when
> > running 64 idle guest due to the two periodic timers. After investigation, I
> found
> > the two periodic timer is used to update RTC clock, check update-ended and
> > check alarm. The following patch achieves the same goal w/o always running
> the
> > periodic timer.
> > For rtc clock:  the per domain variable time_offset_seconds is used to 
> > record
> > the offset between the domain and wall clock. So we can get the domain rtc
> > directly by calculating time_offset_seconds with wall clock.
> > For update-ended check: use a timer to emulate it , and the timer runs only
> > when the last update-ended interrupt flag(UF) is cleared. If the UF already 
> > set,
> > there is no need to set it again.
> > For alarm check: also use a timer to emulate it, and the timer runs only 
> > when
> the
> > flag of alarm interrupt enable bit is set.
> >
> > The logic is a little different between the update-ended check and alarm 
> > check.
> > For update-ended check ,we use UF(update-ended flag) as the judgment and
> > use AIE(alarm interrupt enable flag) for alarm check. This is because OS 
> > may poll
> > the UF bit to check whether the update cycle is finished.(UF bit change 
> > from 0
> to
> > 1 means the update cycle ended). So we need to run the timer when UF bit is
> > cleared.
> > ---
> > Yang Zhang (5):
> >     RTC: use offset to caculatet rtc clock
> >     RTC: fix 12-hour mode
> >     RTC: Add UIP(update in progress) check logic
> >     RTC: Add RTC update-ended interrupt support
> >     RTC: Add alarm support
> >
> > best regards
> > yang
> 
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