KVM: ppc: Implement in-kernel exit timing statistics
Existing KVM statistics are either just counters (kvm_stat) reported for
KVM generally or trace based aproaches like kvm_trace.
For KVM on powerpc we had the need to track the timings of the different exit
types. While this could be achieved parsing data created with a kvm_trace
extension this adds too much overhead (at least on embedded PowerPC) slowing
down the workloads we wanted to measure.
Therefore this patch adds a in-kernel exit timing statistic to the powerpc kvm
code. These statistic is available per vm&vcpu under the kvm debugfs directory.
As this statistic is low, but still some overhead it can be enabled via a
.config entry and should be off by default.
Since this patch touched all powerpc kvm_stat code anyway this code is now
merged and simplified together with the exit timing statistic code (still
working with exit timing disabled in .config).
Signed-off-by: Christian Ehrhardt <ehrhardt@linux.vnet.ibm.com>
Signed-off-by: Hollis Blanchard <hollisb@us.ibm.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
diff --git a/arch/powerpc/kvm/Kconfig b/arch/powerpc/kvm/Kconfig
index e4ab1c7..6dbdc48 100644
--- a/arch/powerpc/kvm/Kconfig
+++ b/arch/powerpc/kvm/Kconfig
@@ -32,6 +32,17 @@
If unsure, say N.
+config KVM_EXIT_TIMING
+ bool "Detailed exit timing"
+ depends on KVM
+ ---help---
+ Calculate elapsed time for every exit/enter cycle. A per-vcpu
+ report is available in debugfs kvm/vm#_vcpu#_timing.
+ The overhead is relatively small, however it is not recommended for
+ production environments.
+
+ If unsure, say N.
+
config KVM_TRACE
bool "KVM trace support"
depends on KVM && MARKERS && SYSFS