Re: [PATCH v2 4/6] KVM: VMX: dynamise PLE window

["Radim Krčmář" <rkrcmar@redhat.com>]

2014-08-21 10:24+0200, Paolo Bonzini:
> Il 20/08/2014 22:53, Radim Krčmář ha scritto:
> > +static void update_ple_window_actual_max(void)
> > +{
> > +	ple_window_actual_max =
> > +			__shrink_ple_window(max(ple_window_max, ple_window),
> 
> Why the max() here?

To have ple_window act as a ple_window_min as well.
(When we are already preventing most stupid choices.)

And it's cheap ... I can add comment to this function :)

> > +			                    ple_window_grow, INT_MIN);
> 
> This should be 0 (in fact you can probably make everything unsigned now
> that you've sorted out the overflows).

Not in v2:
  val = min(vmx->ple_window, ple_window_actual_max);
  val += ple_window_grow;
  vmx->ple_window = val;
so we need to dip below zero to allow all possible grows.

(I'm not sure if anyone is ever going to use the additive option, so
 getting rid of it is also a valid choice -- code would be nicer.)