KVM: selftests: randomize page access order

Create the ability to randomize page access order with the -a
argument. This includes the possibility that the same pages may be hit
multiple times during an iteration or not at all.

Population has random access as false to ensure all pages will be
touched by population and avoid page faults in late dirty memory that
would pollute the test results.

Signed-off-by: Colton Lewis <coltonlewis@google.com>
Reviewed-by: David Matlack <dmatlack@google.com>
Link: https://lore.kernel.org/r/20221107182208.479157-5-coltonlewis@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>

1 files changed, 9 insertions, 2 deletions

diff --git a/tools/testing/selftests/kvm/dirty_log_perf_test.c b/tools/testing/selftests/kvm/dirty_log_perf_test.c
index e9ce50fe7295..47cbda3580fd 100644
--- a/tools/testing/selftests/kvm/dirty_log_perf_test.c
+++ b/tools/testing/selftests/kvm/dirty_log_perf_test.c
@@ -133,6 +133,7 @@ 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)
@@ -259,6 +260,7 @@ static void run_test(enum vm_guest_mode mode, void *arg)
 	 * would pollute the performance results.
 	 */
 	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 */
@@ -281,6 +283,7 @@ 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) {
 		/*
@@ -364,10 +367,11 @@ 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] [-c physical cpus to run test on]\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"
@@ -434,8 +438,11 @@ int main(int argc, char *argv[])
 
 	guest_modes_append_default();
 
-	while ((opt = getopt(argc, argv, "b:c:eghi:m:nop:r:s:v:x:w:")) != -1) {
+	while ((opt = getopt(argc, argv, "ab:c:eghi:m:nop:r:s:v:x:w:")) != -1) {
 		switch (opt) {
+		case 'a':
+			p.random_access = true;
+			break;
 		case 'b':
 			guest_percpu_mem_size = parse_size(optarg);
 			break;