On Fri, Sep 09, 2022 at 12:43:00PM +0000, Colton Lewis wrote:
> Create the ability to randomize page access order with the -a
> argument, including the possibility that the same pages may be hit
> multiple times during an iteration or not at all.
>
> Population sets random access to false.
Please make sure to also explain the why in addition to the what.
>
> Signed-off-by: Colton Lewis <coltonlewis@xxxxxxxxxx>
> ---
> tools/testing/selftests/kvm/dirty_log_perf_test.c | 11 +++++++++--
> .../selftests/kvm/include/perf_test_util.h | 2 ++
> tools/testing/selftests/kvm/lib/perf_test_util.c | 15 ++++++++++++++-
> 3 files changed, 25 insertions(+), 3 deletions(-)
>
> diff --git a/tools/testing/selftests/kvm/dirty_log_perf_test.c b/tools/testing/selftests/kvm/dirty_log_perf_test.c
> index c2ad299b3760..3639d5f95033 100644
> --- a/tools/testing/selftests/kvm/dirty_log_perf_test.c
> +++ b/tools/testing/selftests/kvm/dirty_log_perf_test.c
> @@ -127,6 +127,7 @@ struct test_params {
> int slots;
> uint32_t write_percent;
> uint32_t random_seed;
> + bool random_access;
> };
>
> static void toggle_dirty_logging(struct kvm_vm *vm, int slots, bool enable)
> @@ -248,6 +249,7 @@ static void run_test(enum vm_guest_mode mode, void *arg)
> vcpu_last_completed_iteration[vcpu_id] = -1;
>
> perf_test_set_write_percent(vm, 100);
> + perf_test_set_random_access(vm, false);
> perf_test_start_vcpu_threads(nr_vcpus, vcpu_worker);
>
> /* Allow the vCPUs to populate memory */
> @@ -270,6 +272,7 @@ static void run_test(enum vm_guest_mode mode, void *arg)
> ts_diff.tv_sec, ts_diff.tv_nsec);
>
> perf_test_set_write_percent(vm, p->write_percent);
> + perf_test_set_random_access(vm, p->random_access);
>
> while (iteration < p->iterations) {
> /*
> @@ -341,10 +344,11 @@ static void run_test(enum vm_guest_mode mode, void *arg)
> static void help(char *name)
> {
> puts("");
> - printf("usage: %s [-h] [-i iterations] [-p offset] [-g] "
> + printf("usage: %s [-h] [-a] [-i iterations] [-p offset] [-g] "
> "[-m mode] [-n] [-b vcpu bytes] [-v vcpus] [-o] [-r random seed ] [-s mem type]"
> "[-x memslots] [-w percentage]\n", name);
> puts("");
> + printf(" -a: access memory randomly rather than in order.\n");
> printf(" -i: specify iteration counts (default: %"PRIu64")\n",
> TEST_HOST_LOOP_N);
> printf(" -g: Do not enable KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2. This\n"
> @@ -396,8 +400,11 @@ int main(int argc, char *argv[])
>
> guest_modes_append_default();
>
> - while ((opt = getopt(argc, argv, "ghi:p:m:nb:v:or:s:x:w:")) != -1) {
> + while ((opt = getopt(argc, argv, "aghi:p:m:nb:v:or:s:x:w:")) != -1) {
> switch (opt) {
> + case 'a':
> + p.random_access = true;
> + break;
> case 'g':
> dirty_log_manual_caps = 0;
> break;
> diff --git a/tools/testing/selftests/kvm/include/perf_test_util.h b/tools/testing/selftests/kvm/include/perf_test_util.h
> index f93f2ea7c6a3..d9664a31e01c 100644
> --- a/tools/testing/selftests/kvm/include/perf_test_util.h
> +++ b/tools/testing/selftests/kvm/include/perf_test_util.h
> @@ -39,6 +39,7 @@ struct perf_test_args {
>
> /* Run vCPUs in L2 instead of L1, if the architecture supports it. */
> bool nested;
> + bool random_access;
>
> struct perf_test_vcpu_args vcpu_args[KVM_MAX_VCPUS];
> };
> @@ -53,6 +54,7 @@ void perf_test_destroy_vm(struct kvm_vm *vm);
>
> void perf_test_set_write_percent(struct kvm_vm *vm, uint32_t write_percent);
> void perf_test_set_random_seed(struct kvm_vm *vm, uint32_t random_seed);
> +void perf_test_set_random_access(struct kvm_vm *vm, bool random_access);
>
> void perf_test_start_vcpu_threads(int vcpus, void (*vcpu_fn)(struct perf_test_vcpu_args *));
> void perf_test_join_vcpu_threads(int vcpus);
> diff --git a/tools/testing/selftests/kvm/lib/perf_test_util.c b/tools/testing/selftests/kvm/lib/perf_test_util.c
> index 12a3597be1f9..ce657fa92f05 100644
> --- a/tools/testing/selftests/kvm/lib/perf_test_util.c
> +++ b/tools/testing/selftests/kvm/lib/perf_test_util.c
> @@ -46,6 +46,7 @@ void perf_test_guest_code(uint32_t vcpu_id)
> struct perf_test_vcpu_args *vcpu_args = &pta->vcpu_args[vcpu_id];
> uint64_t gva;
> uint64_t pages;
> + uint64_t addr;
> int i;
> uint32_t rand = pta->random_seed + vcpu_id;
>
> @@ -57,7 +58,13 @@ void perf_test_guest_code(uint32_t vcpu_id)
>
> while (true) {
> for (i = 0; i < pages; i++) {
> - uint64_t addr = gva + (i * pta->guest_page_size);
> + guest_random(&rand);
> +
> + if (pta->random_access)
> + addr = gva + ((rand % pages) * pta->guest_page_size);
> + else
> + addr = gva + (i * pta->guest_page_size);
> +
> guest_random(&rand);
Is it on purpose use a separate random number for access offset and
read/write?
>
> if (rand % 100 < pta->write_percent)
> @@ -233,6 +240,12 @@ void perf_test_set_random_seed(struct kvm_vm *vm, uint32_t random_seed)
> sync_global_to_guest(vm, perf_test_args.random_seed);
> }
>
> +void perf_test_set_random_access(struct kvm_vm *vm, bool random_access)
> +{
> + perf_test_args.random_access = random_access;
> + sync_global_to_guest(vm, perf_test_args.random_access);
> +}
> +
> uint64_t __weak perf_test_nested_pages(int nr_vcpus)
> {
> return 0;
> --
> 2.37.2.789.g6183377224-goog
>
