From mboxrd@z Thu Jan  1 00:00:00 1970
From: Radim =?utf-8?B?S3LEjW3DocWZ?= <rkrcmar@redhat.com>
Subject: Re: [PATCH v2 4/6] KVM: VMX: dynamise PLE window
Date: Thu, 21 Aug 2014 13:47:40 +0200
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Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
	Gleb Natapov <gleb@kernel.org>,
	Raghavendra KT <raghavendra.kt@linux.vnet.ibm.com>,
	Vinod Chegu <chegu_vinod@hp.com>,
	Hui-Zhi <hui-zhi.zhao@hp.com>,
	Christian Borntraeger <borntraeger@de.ibm.com>
To: Paolo Bonzini <pbonzini@redhat.com>
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2014-08-21 10:24+0200, Paolo Bonzini:
> Il 20/08/2014 22:53, Radim Kr=C4=8Dm=C3=A1=C5=99 ha scritto:
> > +static void update_ple_window_actual_max(void)
> > +{
> > +	ple_window_actual_max =3D
> > +			__shrink_ple_window(max(ple_window_max, ple_window),
>=20
> 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);
>=20
> This should be 0 (in fact you can probably make everything unsigned n=
ow
> that you've sorted out the overflows).

Not in v2:
  val =3D min(vmx->ple_window, ple_window_actual_max);
  val +=3D ple_window_grow;
  vmx->ple_window =3D 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.)