RE: [Xen-devel] [PATCH] Fix hvm guest time to be more accurate

["Dong, Eddie" <eddie.dong@xxxxxxxxx>]

Dave Winchell wrote:
> Eddie,
> 
> I implemented #2B and ran a three hour test
> with sles9-64 and rh4u4-64 guests. Each guest had 8 vcpus
> and the box was Intel with 2 physical processors.
> The guests were running large loads.
> Clock was pit. This is my usual test setup, except that I just
> as often used AMD nodes with more processors.
> 
> The time error was .02%, good enough for ntpd.
> 
> The implementation keeps a constant guest tsc offset.
> There is no pending_nr cancellation.
> When the vpt.c timer expires, it only increments pending_nr
> if its value is zero.
> Missed_ticks() is still calculated, but only to update the new
> timeout value. There is no adjustment to the tsc offset
> (set_guest_time()) 
> at clock interrupt delivery time nor at re-scheduling time.
> 
> So, I like this method better than the pending_nr subtract.
> I'm going to work on this some more and, if all goes well,
> propose a new code submission soon.
> I'll put some kind of policy switch in too, which we can discuss
> and modify, but it will be along the lines of what we discussed below.
> 
> Thanks for your input!
> 
> -Dave
> 


Haitao Shai may posted his patch, can u check if there are something
missed?
thx,eddie

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