linux-kernel - Re: [PATCH 5/9] KVM: VMX: clamp PLE window

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Date:	Wed, 20 Aug 2014 14:46:08 +0200
From:	Radim Krčmář <rkrcmar@...hat.com>
To:	Paolo Bonzini <pbonzini@...hat.com>
Cc:	kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
	Gleb Natapov <gleb@...nel.org>,
	Raghavendra KT <raghavendra.kt@...ux.vnet.ibm.com>,
	Vinod Chegu <chegu_vinod@...com>, Hui-Zhi <hui-zhi.zhao@...com>
Subject: Re: [PATCH 5/9] KVM: VMX: clamp PLE window

2014-08-20 09:18+0200, Paolo Bonzini:
> Il 19/08/2014 22:35, Radim Krčmář ha scritto:
> > Modifications could get unwanted values of PLE window. (low or negative)
> > Use ple_window and the maximal value that cannot overflow as bounds.
> > 
> > ple_window_max defaults to a very high value, but it would make sense to
> > set it to some fraction of the scheduler tick.
> > 
> > Signed-off-by: Radim Krčmář <rkrcmar@...hat.com>
> > ---
> Please introduce a dynamic overflow-avoiding ple_window_max (like what
> you have in patch 9) already in patch 4...
> 
> >  static void shrink_ple_window(struct kvm_vcpu *vcpu)
> > @@ -5720,7 +5724,7 @@ static void shrink_ple_window(struct kvm_vcpu *vcpu)
> >  	else
> >  		new = old - ple_window_shrink;
> >  
> > -	vmx->ple_window = new;
> > +	vmx->ple_window = max(new, ple_window);
> 
> ... and also squash this in patch 4.
> 
> This patch can then introduce the ple_window_max module parameter (using
> module_param_cb to avoid overflows).

Will do.

---
It is going to make the patches slightly harder to review;
Are we doing it because git doesn't bisect on series boundaries?
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