On Wed, Aug 17, 2022 at 09:41:44PM +0000, Colton Lewis wrote:
> Create for each vcpu an array of random numbers to be used as a source
> of randomness when executing guest code. Randomness should be useful
> for approaching more realistic conditions in dirty_log_perf_test.
>
> Create a -r argument to specify a random seed. If no argument
> is provided, the seed defaults to the current Unix timestamp.
>
> The random arrays are allocated and filled as part of VM creation. The
> additional memory used is one 32-bit number per guest VM page to
> ensure one number for each iteration of the inner loop of guest_code.
>
> Signed-off-by: Colton Lewis <coltonlewis@xxxxxxxxxx>
> ---
> .../selftests/kvm/dirty_log_perf_test.c | 11 ++++-
> .../selftests/kvm/include/perf_test_util.h | 3 ++
> .../selftests/kvm/lib/perf_test_util.c | 45 ++++++++++++++++++-
> 3 files changed, 55 insertions(+), 4 deletions(-)
>
> diff --git a/tools/testing/selftests/kvm/dirty_log_perf_test.c b/tools/testing/selftests/kvm/dirty_log_perf_test.c
> index f99e39a672d3..362b946019e9 100644
> --- a/tools/testing/selftests/kvm/dirty_log_perf_test.c
> +++ b/tools/testing/selftests/kvm/dirty_log_perf_test.c
> @@ -132,6 +132,7 @@ struct test_params {
> bool partition_vcpu_memory_access;
> enum vm_mem_backing_src_type backing_src;
> int slots;
> + uint32_t random_seed;
> };
>
> static void toggle_dirty_logging(struct kvm_vm *vm, int slots, bool enable)
> @@ -225,6 +226,7 @@ static void run_test(enum vm_guest_mode mode, void *arg)
> p->slots, p->backing_src,
> p->partition_vcpu_memory_access);
>
> + perf_test_set_random_seed(vm, p->random_seed);
> perf_test_set_wr_fract(vm, p->wr_fract);
>
> guest_num_pages = (nr_vcpus * guest_percpu_mem_size) >> vm->page_shift;
> @@ -352,7 +354,7 @@ static void help(char *name)
> {
> puts("");
> printf("usage: %s [-h] [-i iterations] [-p offset] [-g] "
> - "[-m mode] [-n] [-b vcpu bytes] [-v vcpus] [-o] [-s mem type]"
> + "[-m mode] [-n] [-b vcpu bytes] [-v vcpus] [-o] [-r random seed ] [-s mem type]"
> "[-x memslots]\n", name);
> puts("");
> printf(" -i: specify iteration counts (default: %"PRIu64")\n",
> @@ -380,6 +382,7 @@ static void help(char *name)
> printf(" -v: specify the number of vCPUs to run.\n");
> printf(" -o: Overlap guest memory accesses instead of partitioning\n"
> " them into a separate region of memory for each vCPU.\n");
> + printf(" -r: specify the starting random seed.\n");
> backing_src_help("-s");
> printf(" -x: Split the memory region into this number of memslots.\n"
> " (default: 1)\n");
> @@ -396,6 +399,7 @@ int main(int argc, char *argv[])
> .partition_vcpu_memory_access = true,
> .backing_src = DEFAULT_VM_MEM_SRC,
> .slots = 1,
> + .random_seed = time(NULL),
> };
> int opt;
>
> @@ -406,7 +410,7 @@ int main(int argc, char *argv[])
>
> guest_modes_append_default();
>
> - while ((opt = getopt(argc, argv, "eghi:p:m:nb:f:v:os:x:")) != -1) {
> + while ((opt = getopt(argc, argv, "eghi:p:m:nb:f:v:or:s:x:")) != -1) {
> switch (opt) {
> case 'e':
> /* 'e' is for evil. */
> @@ -442,6 +446,9 @@ int main(int argc, char *argv[])
> case 'o':
> p.partition_vcpu_memory_access = false;
> break;
> + case 'r':
> + p.random_seed = atoi(optarg);
> + break;
> case 's':
> p.backing_src = parse_backing_src_type(optarg);
> break;
> diff --git a/tools/testing/selftests/kvm/include/perf_test_util.h b/tools/testing/selftests/kvm/include/perf_test_util.h
> index eaa88df0555a..9517956424fc 100644
> --- a/tools/testing/selftests/kvm/include/perf_test_util.h
> +++ b/tools/testing/selftests/kvm/include/perf_test_util.h
> @@ -23,6 +23,7 @@ struct perf_test_vcpu_args {
> uint64_t gpa;
> uint64_t gva;
> uint64_t pages;
> + vm_vaddr_t random_array;
>
> /* Only used by the host userspace part of the vCPU thread */
> struct kvm_vcpu *vcpu;
> @@ -35,6 +36,7 @@ struct perf_test_args {
> uint64_t gpa;
> uint64_t size;
> uint64_t guest_page_size;
> + uint32_t random_seed;
> int wr_fract;
>
> /* Run vCPUs in L2 instead of L1, if the architecture supports it. */
> @@ -52,6 +54,7 @@ struct kvm_vm *perf_test_create_vm(enum vm_guest_mode mode, int nr_vcpus,
> void perf_test_destroy_vm(struct kvm_vm *vm);
>
> void perf_test_set_wr_fract(struct kvm_vm *vm, int wr_fract);
> +void perf_test_set_random_seed(struct kvm_vm *vm, uint32_t random_seed);
>
> 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 9618b37c66f7..8d85923acb4e 100644
> --- a/tools/testing/selftests/kvm/lib/perf_test_util.c
> +++ b/tools/testing/selftests/kvm/lib/perf_test_util.c
> @@ -70,6 +70,35 @@ void perf_test_guest_code(uint32_t vcpu_idx)
> }
> }
>
> +void perf_test_alloc_random_arrays(uint32_t nr_vcpus, uint32_t nr_randoms)
> +{
> + struct perf_test_args *pta = &perf_test_args;
> +
> + for (uint32_t i = 0; i < nr_vcpus; i++) {
> + pta->vcpu_args[i].random_array = vm_vaddr_alloc(
> + pta->vm,
> + nr_randoms * sizeof(uint32_t),
> + KVM_UTIL_MIN_VADDR);
> + pr_debug("Random row %d vaddr: %p.\n", i, (void *)pta->vcpu_args[i].random_array);
> + }
> +}
> +
> +void perf_test_fill_random_arrays(uint32_t nr_vcpus, uint32_t nr_randoms)
> +{
> + struct perf_test_args *pta = &perf_test_args;
> + uint32_t *host_row;
> +
> + for (uint32_t i = 0; i < nr_vcpus; i++) {
> + host_row = addr_gva2hva(pta->vm, pta->vcpu_args[i].random_array);
> +
> + for (uint32_t j = 0; j < nr_randoms; j++)
> + host_row[j] = random();
> +
> + pr_debug("New randoms row %d: %d, %d, %d...\n",
> + i, host_row[0], host_row[1], host_row[2]);
> + }
> +}
> +
> void perf_test_setup_vcpus(struct kvm_vm *vm, int nr_vcpus,
> struct kvm_vcpu *vcpus[],
> uint64_t vcpu_memory_bytes,
> @@ -120,8 +149,9 @@ struct kvm_vm *perf_test_create_vm(enum vm_guest_mode mode, int nr_vcpus,
>
> pr_info("Testing guest mode: %s\n", vm_guest_mode_string(mode));
>
> - /* By default vCPUs will write to memory. */
> - pta->wr_fract = 1;
> + /* Set perf_test_args defaults. */
> + pta->wr_fract = 100;
This is not needed in this commit. It's changing the behavior at the
current commit, as it's now defaulting to 0% reads (using the current
check in guest_code()).
> + pta->random_seed = time(NULL);
>
> /*
> * Snapshot the non-huge page size. This is used by the guest code to
> @@ -211,6 +241,11 @@ struct kvm_vm *perf_test_create_vm(enum vm_guest_mode mode, int nr_vcpus,
>
> ucall_init(vm, NULL);
>
> + srandom(perf_test_args.random_seed);
> + pr_info("Random seed: %d\n", perf_test_args.random_seed);
> + perf_test_alloc_random_arrays(nr_vcpus, vcpu_memory_bytes >> vm->page_shift);
> + perf_test_fill_random_arrays(nr_vcpus, vcpu_memory_bytes >> vm->page_shift);
> +
> /* Export the shared variables to the guest. */
> sync_global_to_guest(vm, perf_test_args);
>
> @@ -229,6 +264,12 @@ void perf_test_set_wr_fract(struct kvm_vm *vm, int wr_fract)
> sync_global_to_guest(vm, perf_test_args);
> }
>
> +void perf_test_set_random_seed(struct kvm_vm *vm, uint32_t random_seed)
> +{
> + perf_test_args.random_seed = random_seed;
> + sync_global_to_guest(vm, perf_test_args);
> +}
> +
> uint64_t __weak perf_test_nested_pages(int nr_vcpus)
> {
> return 0;
> --
> 2.37.1.595.g718a3a8f04-goog
>
