Re: [RFC PATCH v2 2/7] KVM: selftests: Use flag CLOCK_MONOTONIC_RAW for timing

On Thu, Feb 25, 2021 at 01:59:35PM +0800, Yanan Wang wrote:

In addition to function of CLOCK_MONOTONIC, flag CLOCK_MONOTONIC_RAW can also shield possiable impact of NTP, which can provide more robustness.

IIRC, this should include

Suggested-by: Vitaly Kuznetsov vkuznets@redhat.com

Signed-off-by: Yanan Wang wangyanan55@huawei.com

tools/testing/selftests/kvm/demand_paging_test.c | 8 ++++---- tools/testing/selftests/kvm/dirty_log_perf_test.c | 14 +++++++------- tools/testing/selftests/kvm/lib/test_util.c | 2 +- tools/testing/selftests/kvm/steal_time.c | 4 ++-- 4 files changed, 14 insertions(+), 14 deletions(-)

diff --git a/tools/testing/selftests/kvm/demand_paging_test.c b/tools/testing/selftests/kvm/demand_paging_test.c index 5f7a229c3af1..efbf0c1e9130 100644 --- a/tools/testing/selftests/kvm/demand_paging_test.c +++ b/tools/testing/selftests/kvm/demand_paging_test.c @@ -53,7 +53,7 @@ static void *vcpu_worker(void *data) vcpu_args_set(vm, vcpu_id, 1, vcpu_id); run = vcpu_state(vm, vcpu_id);

• clock_gettime(CLOCK_MONOTONIC, &start);

• clock_gettime(CLOCK_MONOTONIC_RAW, &start);

/* Let the guest access its memory */ ret = _vcpu_run(vm, vcpu_id); @@ -86,7 +86,7 @@ static int handle_uffd_page_request(int uffd, uint64_t addr) copy.len = perf_test_args.host_page_size; copy.mode = 0;

• clock_gettime(CLOCK_MONOTONIC, &start);

• clock_gettime(CLOCK_MONOTONIC_RAW, &start);

r = ioctl(uffd, UFFDIO_COPY, &copy); if (r == -1) { @@ -123,7 +123,7 @@ static void *uffd_handler_thread_fn(void *arg) struct timespec start; struct timespec ts_diff;

• clock_gettime(CLOCK_MONOTONIC, &start);

• clock_gettime(CLOCK_MONOTONIC_RAW, &start); while (!quit_uffd_thread) { struct uffd_msg msg; struct pollfd pollfd[2];

@@ -336,7 +336,7 @@ static void run_test(enum vm_guest_mode mode, void *arg) pr_info("Finished creating vCPUs and starting uffd threads\n");

• clock_gettime(CLOCK_MONOTONIC, &start);

• clock_gettime(CLOCK_MONOTONIC_RAW, &start);

for (vcpu_id = 0; vcpu_id < nr_vcpus; vcpu_id++) { pthread_create(&vcpu_threads[vcpu_id], NULL, vcpu_worker, diff --git a/tools/testing/selftests/kvm/dirty_log_perf_test.c b/tools/testing/selftests/kvm/dirty_log_perf_test.c index 04a2641261be..6cff4ccf9525 100644 --- a/tools/testing/selftests/kvm/dirty_log_perf_test.c +++ b/tools/testing/selftests/kvm/dirty_log_perf_test.c @@ -50,7 +50,7 @@ static void *vcpu_worker(void *data) while (!READ_ONCE(host_quit)) { int current_iteration = READ_ONCE(iteration);

• clock_gettime(CLOCK_MONOTONIC, &start);
  

• clock_gettime(CLOCK_MONOTONIC_RAW, &start);
  

  ret = _vcpu_run(vm, vcpu_id); ts_diff = timespec_elapsed(start);

@@ -141,7 +141,7 @@ static void run_test(enum vm_guest_mode mode, void *arg) iteration = 0; host_quit = false;

• clock_gettime(CLOCK_MONOTONIC, &start);

• clock_gettime(CLOCK_MONOTONIC_RAW, &start); for (vcpu_id = 0; vcpu_id < nr_vcpus; vcpu_id++) { vcpu_last_completed_iteration[vcpu_id] = -1;

@@ -162,7 +162,7 @@ static void run_test(enum vm_guest_mode mode, void *arg) ts_diff.tv_sec, ts_diff.tv_nsec); /* Enable dirty logging */

• clock_gettime(CLOCK_MONOTONIC, &start);

• clock_gettime(CLOCK_MONOTONIC_RAW, &start); vm_mem_region_set_flags(vm, PERF_TEST_MEM_SLOT_INDEX, KVM_MEM_LOG_DIRTY_PAGES); ts_diff = timespec_elapsed(start);

@@ -174,7 +174,7 @@ static void run_test(enum vm_guest_mode mode, void *arg) * Incrementing the iteration number will start the vCPUs * dirtying memory again. */

• clock_gettime(CLOCK_MONOTONIC, &start);
  

• clock_gettime(CLOCK_MONOTONIC_RAW, &start);
  

  iteration++;

pr_debug("Starting iteration %d\n", iteration); @@ -189,7 +189,7 @@ static void run_test(enum vm_guest_mode mode, void *arg) pr_info("Iteration %d dirty memory time: %ld.%.9lds\n", iteration, ts_diff.tv_sec, ts_diff.tv_nsec);

• clock_gettime(CLOCK_MONOTONIC, &start);
  

• clock_gettime(CLOCK_MONOTONIC_RAW, &start);
  

  kvm_vm_get_dirty_log(vm, PERF_TEST_MEM_SLOT_INDEX, bmap);

ts_diff = timespec_elapsed(start); @@ -199,7 +199,7 @@ static void run_test(enum vm_guest_mode mode, void *arg) iteration, ts_diff.tv_sec, ts_diff.tv_nsec); if (dirty_log_manual_caps) {

• 	clock_gettime(CLOCK_MONOTONIC, &start);
  

• 	clock_gettime(CLOCK_MONOTONIC_RAW, &start);
  kvm_vm_clear_dirty_log(vm, PERF_TEST_MEM_SLOT_INDEX, bmap, 0,
  		       host_num_pages);
  

@@ -212,7 +212,7 @@ static void run_test(enum vm_guest_mode mode, void *arg) } /* Disable dirty logging */

• clock_gettime(CLOCK_MONOTONIC, &start);

• clock_gettime(CLOCK_MONOTONIC_RAW, &start); vm_mem_region_set_flags(vm, PERF_TEST_MEM_SLOT_INDEX, 0); ts_diff = timespec_elapsed(start); pr_info("Disabling dirty logging time: %ld.%.9lds\n",

diff --git a/tools/testing/selftests/kvm/lib/test_util.c b/tools/testing/selftests/kvm/lib/test_util.c index 906c955384e2..c7c0627c6842 100644 --- a/tools/testing/selftests/kvm/lib/test_util.c +++ b/tools/testing/selftests/kvm/lib/test_util.c @@ -89,7 +89,7 @@ struct timespec timespec_elapsed(struct timespec start) { struct timespec end;

• clock_gettime(CLOCK_MONOTONIC, &end);

• clock_gettime(CLOCK_MONOTONIC_RAW, &end); return timespec_sub(end, start);

} diff --git a/tools/testing/selftests/kvm/steal_time.c b/tools/testing/selftests/kvm/steal_time.c index fcc840088c91..5bc582d3f2a2 100644 --- a/tools/testing/selftests/kvm/steal_time.c +++ b/tools/testing/selftests/kvm/steal_time.c @@ -237,11 +237,11 @@ static void *do_steal_time(void *arg) { struct timespec ts, stop;

• clock_gettime(CLOCK_MONOTONIC, &ts);

• clock_gettime(CLOCK_MONOTONIC_RAW, &ts); stop = timespec_add_ns(ts, MIN_RUN_DELAY_NS);

while (1) {

• clock_gettime(CLOCK_MONOTONIC, &ts);
  

• clock_gettime(CLOCK_MONOTONIC_RAW, &ts);
  

  if (timespec_to_ns(timespec_sub(ts, stop)) >= 0) break; }

-- 2.19.1