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

wangyanan (Y) Thu, 25 Feb 2021 18:50:29 -0800


On 2021/2/26 2:54, Andrew Jones wrote:

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 <vkuzn...@redhat.com>


Oh, sorry for my rashness. I will include it in v3.

Thanks,

Yanan

Signed-off-by: Yanan Wang <wangyana...@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

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

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