svn commit: r325108 - head/sys/amd64/vmm/io

[Ian Lepore]

On Sun, 2017-10-29 at 15:15 -0700, Peter Grehan wrote:
> > 
> > > 
> > >    Improve the performance of the hpet timer in bhyve guests by making the
> > >    timer frequency a power of two.  This changes the frequency from 10 to
> > >    16.7 MHz (2 ^ 24 HZ).  Using a power of two avoids roundoff errors when
> > >    doing arithmetic in sbintime_t units.
> > >    
> > >    Testing shows this can fix erratic ntpd behavior in guests using the
> > >    hpet timer (which is the default for multicore guests).
> > >    
> > >    Reported by:	bsam@
> > > 
> > > Modified:
> > >    head/sys/amd64/vmm/io/vhpet.c
>   In the future please respect MAINTAINERS and file a phab review for 
> code in this area.
> 
> later,
> 
> Peter.
> 
> 

In fact I did check maintainers, and I just now checked it again, and
seeing nothing on-point, wrote a really snarky reply.

Luckily, before hitting send I realized you wouldn't have said anything
unless there was an entry in there, so I checked like 4 more times
before I noticed the line that begins vmm(4).  I had been looking for a
line that began with sys/amd64.

So... sorry about that.  Should I revert it and open a review?

Longer-term, I was hoping to find some time over the next few weeks to
further explore the roundoff errors in the timers and attempt a better
fix, and I was definitely intending to put that up for review
(especially because it involves math, and I'm always better off asking
for help with that).

-- Ian