diff options
| -rw-r--r-- | tools/testing/selftests/kvm/x86_64/hyperv_clock.c | 10 |
1 files changed, 7 insertions, 3 deletions
diff --git a/tools/testing/selftests/kvm/x86_64/hyperv_clock.c b/tools/testing/selftests/kvm/x86_64/hyperv_clock.c index e0b2bb1339b1..3330fb183c68 100644 --- a/tools/testing/selftests/kvm/x86_64/hyperv_clock.c +++ b/tools/testing/selftests/kvm/x86_64/hyperv_clock.c @@ -44,7 +44,7 @@ static inline void nop_loop(void) { int i; - for (i = 0; i < 1000000; i++) + for (i = 0; i < 100000000; i++) asm volatile("nop"); } @@ -56,12 +56,14 @@ static inline void check_tsc_msr_rdtsc(void) tsc_freq = rdmsr(HV_X64_MSR_TSC_FREQUENCY); GUEST_ASSERT(tsc_freq > 0); - /* First, check MSR-based clocksource */ + /* For increased accuracy, take mean rdtsc() before and afrer rdmsr() */ r1 = rdtsc(); t1 = rdmsr(HV_X64_MSR_TIME_REF_COUNT); + r1 = (r1 + rdtsc()) / 2; nop_loop(); r2 = rdtsc(); t2 = rdmsr(HV_X64_MSR_TIME_REF_COUNT); + r2 = (r2 + rdtsc()) / 2; GUEST_ASSERT(r2 > r1 && t2 > t1); @@ -181,12 +183,14 @@ static void host_check_tsc_msr_rdtsc(struct kvm_vm *vm) tsc_freq = vcpu_get_msr(vm, VCPU_ID, HV_X64_MSR_TSC_FREQUENCY); TEST_ASSERT(tsc_freq > 0, "TSC frequency must be nonzero"); - /* First, check MSR-based clocksource */ + /* For increased accuracy, take mean rdtsc() before and afrer ioctl */ r1 = rdtsc(); t1 = vcpu_get_msr(vm, VCPU_ID, HV_X64_MSR_TIME_REF_COUNT); + r1 = (r1 + rdtsc()) / 2; nop_loop(); r2 = rdtsc(); t2 = vcpu_get_msr(vm, VCPU_ID, HV_X64_MSR_TIME_REF_COUNT); + r2 = (r2 + rdtsc()) / 2; TEST_ASSERT(t2 > t1, "Time reference MSR is not monotonic (%ld <= %ld)", t1, t2); |