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authorMarc Zyngier <marc.zyngier@arm.com>2018-06-21 12:43:59 +0300
committerMarc Zyngier <marc.zyngier@arm.com>2018-07-09 13:38:24 +0300
commitde73708915adc1b3f05e617a86da6b2d68fae141 (patch)
tree37f70c868acf33f7645e67c42b599cd5034614c4 /virt
parent0a72a5ab9feb8ba6101b00bbcac14cdbae1d1df7 (diff)
downloadlinux-de73708915adc1b3f05e617a86da6b2d68fae141.tar.xz
KVM: arm/arm64: Enable adaptative WFE trapping
Trapping blocking WFE is extremely beneficial in situations where the system is oversubscribed, as it allows another thread to run while being blocked. In a non-oversubscribed environment, this is the complete opposite, and trapping WFE is just unnecessary overhead. Let's only enable WFE trapping if the CPU has more than a single task to run (that is, more than just the vcpu thread). Reviewed-by: Christoffer Dall <christoffer.dall@arm.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Diffstat (limited to 'virt')
-rw-r--r--virt/kvm/arm/arm.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c
index 04e554cae3a2..8e66b89a3db2 100644
--- a/virt/kvm/arm/arm.c
+++ b/virt/kvm/arm/arm.c
@@ -30,6 +30,7 @@
#include <linux/kvm.h>
#include <linux/kvm_irqfd.h>
#include <linux/irqbypass.h>
+#include <linux/sched/stat.h>
#include <trace/events/kvm.h>
#include <kvm/arm_pmu.h>
#include <kvm/arm_psci.h>
@@ -380,6 +381,11 @@ void kvm_arch_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
kvm_timer_vcpu_load(vcpu);
kvm_vcpu_load_sysregs(vcpu);
kvm_arch_vcpu_load_fp(vcpu);
+
+ if (single_task_running())
+ vcpu_clear_wfe_traps(vcpu);
+ else
+ vcpu_set_wfe_traps(vcpu);
}
void kvm_arch_vcpu_put(struct kvm_vcpu *vcpu)