Re: [Xen-devel] RE: [PATCH] rendezvous-based local time calibration WOW!

[Keir Fraser <keir.fraser@xxxxxxxxxxxxx>]

On 5/8/08 22:27, "Dan Magenheimer" <dan.magenheimer@xxxxxxxxxx> wrote:

>> No, as it would be incredibly slow on Solaris (I dread to imagine).
> 
> Could be.  On my box (Conroe), trapping tsc in an hvm is faster
> than reading pit or hpet in the hypervisor or in a native OS.

For a PV guest it only punts the monotonicity problem into the hypervisor of
course. You still need to access a shared counter, or use a lock (i.e.,
communication/synchronisation between processors), or be guaranteed that
local counters (TSCs) are driven by a common clock signal with negligible
skew.

 -- Keir



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