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| author | Marc Zyngier <marc.zyngier@arm.com> | 2014-06-20 17:38:14 +0100 |
|---|---|---|
| committer | Will Deacon <will.deacon@arm.com> | 2015-06-01 16:39:55 +0100 |
| commit | 00751da0c0cb4ca2221f1553043acaaaf5df2737 (patch) | |
| tree | f046f088eef86efe4722adf4c5d0742a9d5af5dd | |
| parent | 492aa8f37a1364cf5b53de096782d967ba13d663 (diff) | |
| download | kvmtool-00751da0c0cb4ca2221f1553043acaaaf5df2737.tar.gz | |
kvmtool: ARM: timers: add "always-on" property to the device tree
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.
Acked-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
| -rw-r--r-- | arm/timer.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arm/timer.c b/arm/timer.c index d757c1dd..209251ef 100644 --- a/arm/timer.c +++ b/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)); |