[PATCH v5 3/3] KVM: selftests: randomize page access order

[Colton Lewis <coltonlewis@google.com>]

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.

Signed-off-by: Colton Lewis <coltonlewis@google.com>
---
 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);
 
 			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