The new optional property "always-on" indicates that the timers
are, well, always on when used with KVM.
This allows for substantial performance improvement in the guest
(it switches to NOHZ instead of using a periodic tick per vcpu)
and removes a lot of burden from the host (no need to inject tons
of interrupts with the associated rescheduling overhead).
Old kernels that don't understand this property will simply ignore it.
Signed-off-by: Marc Zyngier <marc.zyng...@arm.com>
---
tools/kvm/arm/timer.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/tools/kvm/arm/timer.c b/tools/kvm/arm/timer.c
index d757c1d..209251e 100644
--- a/tools/kvm/arm/timer.c
+++ b/tools/kvm/arm/timer.c
@@ -33,6 +33,7 @@ void timer__generate_fdt_nodes(void *fdt, struct kvm *kvm,
int *irqs)
_FDT(fdt_begin_node(fdt, "timer"));
_FDT(fdt_property(fdt, "compatible", compatible, sizeof(compatible)));
_FDT(fdt_property(fdt, "interrupts", irq_prop, sizeof(irq_prop)));
+ _FDT(fdt_property(fdt, "always-on", NULL, 0));
if (kvm->cfg.arch.force_cntfrq > 0)
_FDT(fdt_property_cell(fdt, "clock-frequency",
kvm->cfg.arch.force_cntfrq));
_FDT(fdt_end_node(fdt));
--
1.8.3.4
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