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@xxxxxxxxxx> > --- > arch/x86/kvm/vmx.c | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c > index 66259fd..e1192fb 100644 > --- a/arch/x86/kvm/vmx.c > +++ b/arch/x86/kvm/vmx.c > @@ -144,6 +144,10 @@ module_param(ple_window_grow, int, S_IRUGO); > static int ple_window_shrink = KVM_VMX_DEFAULT_PLE_WINDOW_SHRINK; > module_param(ple_window_shrink, int, S_IRUGO); > > +/* Default is to compute the maximum so we can never overflow. */ > +static int ple_window_max = INT_MAX / KVM_VMX_DEFAULT_PLE_WINDOW_GROW; > +module_param(ple_window_max, int, S_IRUGO); > + > extern const ulong vmx_return; > > #define NR_AUTOLOAD_MSRS 8 > @@ -5704,7 +5708,7 @@ static void grow_ple_window(struct kvm_vcpu *vcpu) > else > new = old + ple_window_grow; > > - vmx->ple_window = new; > + vmx->ple_window = min(new, ple_window_max); > } 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). Paolo > } > > /* > -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
