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>
This commit is contained in:
Hollis Blanchard
2008-12-02 15:51:57 -06:00
committed by Avi Kivity
parent c5fbdffbda
commit 73e75b416f
13 changed files with 516 additions and 18 deletions

View File

@ -107,6 +107,18 @@ _GLOBAL(kvmppc_resume_host)
li r6, 1
slw r6, r6, r5
#ifdef CONFIG_KVM_EXIT_TIMING
/* save exit time */
1:
mfspr r7, SPRN_TBRU
mfspr r8, SPRN_TBRL
mfspr r9, SPRN_TBRU
cmpw r9, r7
bne 1b
stw r8, VCPU_TIMING_EXIT_TBL(r4)
stw r9, VCPU_TIMING_EXIT_TBU(r4)
#endif
/* Save the faulting instruction and all GPRs for emulation. */
andi. r7, r6, NEED_INST_MASK
beq ..skip_inst_copy
@ -375,6 +387,18 @@ lightweight_exit:
lwz r3, VCPU_SPRG7(r4)
mtspr SPRN_SPRG7, r3
#ifdef CONFIG_KVM_EXIT_TIMING
/* save enter time */
1:
mfspr r6, SPRN_TBRU
mfspr r7, SPRN_TBRL
mfspr r8, SPRN_TBRU
cmpw r8, r6
bne 1b
stw r7, VCPU_TIMING_LAST_ENTER_TBL(r4)
stw r8, VCPU_TIMING_LAST_ENTER_TBU(r4)
#endif
/* Finish loading guest volatiles and jump to guest. */
lwz r3, VCPU_CTR(r4)
mtctr r3