Re: [PATCH] KVM: selftests: use unified time type for comparison

Sean Christopherson
2023-08-02T19:30:52Z

+Oliver to get input on something beyond non-x86, and because I hate anything
clock related :-)

On Mon, Jul 31, 2023, Bibo Mao wrote:
> With test case kvm_page_table_test, start time is acquired with
> time type CLOCK_MONOTONIC_RAW, however end time in function timespec_elapsed
> is acquired with time type CLOCK_MONOTONIC. This will cause
> inaccurate elapsed time calculation on some platform such as LoongArch.
>
> This patch modified test case kvm_page_table_test, and uses unified
> time type CLOCK_MONOTONIC for start time.

AFAICT, there's zero reason to use CLOCK_MONOTONIC_RAW instead of CLOCK_MONOTONIC.
If there are no objections, I'll take this through kvm-x86/selftests for 6.6.

> Signed-off-by: Bibo Mao <maobibo@loongson.cn>
> ---
> tools/testing/selftests/kvm/kvm_page_table_test.c | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/tools/testing/selftests/kvm/kvm_page_table_test.c b/tools/testing/selftests/kvm/kvm_page_table_test.c
> index b3b00be1ef82..69f26d80c821 100644
> --- a/tools/testing/selftests/kvm/kvm_page_table_test.c
> +++ b/tools/testing/selftests/kvm/kvm_page_table_test.c
> @@ -200,7 +200,7 @@ static void *vcpu_worker(void *data)
> if (READ_ONCE(host_quit))
> return NULL;
>
> - clock_gettime(CLOCK_MONOTONIC_RAW, &start);
> + clock_gettime(CLOCK_MONOTONIC, &start);
> ret = _vcpu_run(vcpu);
> ts_diff = timespec_elapsed(start);
>
> @@ -367,7 +367,7 @@ static void run_test(enum vm_guest_mode mode, void *arg)
> /* Test the stage of KVM creating mappings */
> *current_stage = KVM_CREATE_MAPPINGS;
>
> - clock_gettime(CLOCK_MONOTONIC_RAW, &start);
> + clock_gettime(CLOCK_MONOTONIC, &start);
> vcpus_complete_new_stage(*current_stage);
> ts_diff = timespec_elapsed(start);
>
> @@ -380,7 +380,7 @@ static void run_test(enum vm_guest_mode mode, void *arg)
>
> *current_stage = KVM_UPDATE_MAPPINGS;
>
> - clock_gettime(CLOCK_MONOTONIC_RAW, &start);
> + clock_gettime(CLOCK_MONOTONIC, &start);
> vcpus_complete_new_stage(*current_stage);
> ts_diff = timespec_elapsed(start);
>
> @@ -392,7 +392,7 @@ static void run_test(enum vm_guest_mode mode, void *arg)
>
> *current_stage = KVM_ADJUST_MAPPINGS;
>
> - clock_gettime(CLOCK_MONOTONIC_RAW, &start);
> + clock_gettime(CLOCK_MONOTONIC, &start);
> vcpus_complete_new_stage(*current_stage);
> ts_diff = timespec_elapsed(start);
>
> --
> 2.27.0
>