Why are we using preemption timer on x86?

[Jintack Lim <incredible.tack@xxxxxxxxx>]

Hi,

I'm just wondering what's the reason why we use the preemption timer
instead of emulating VM's timer using hrtimer in software? Is there
anything the the preemption timer can do that can't be done with
hrtimer?

I guess the x86 architecture provides the preemption timer for *some*
reason, but I'm not sure what they are.

Thanks,
Jintack