KVM: selftests: Support multiple slots in dirty_log_perf_test

Introduce a new option to dirty_log_perf_test: -x number_of_slots. This
causes the test to attempt to split the region of memory into the given
number of slots. If the region cannot be evenly divided, the test will
fail.

This allows testing with more than one slot and therefore measure how
performance scales with the number of memslots.

Signed-off-by: David Matlack <dmatlack@google.com>
Message-Id: <20210804222844.1419481-8-dmatlack@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 65 insertions, 11 deletions

diff --git a/tools/testing/selftests/kvm/dirty_log_perf_test.c b/tools/testing/selftests/kvm/dirty_log_perf_test.c
index 80cbd3a748c0..034458dd89a2 100644
--- a/tools/testing/selftests/kvm/dirty_log_perf_test.c
+++ b/tools/testing/selftests/kvm/dirty_log_perf_test.c
@@ -94,8 +94,59 @@ struct test_params {
 	int wr_fract;
 	bool partition_vcpu_memory_access;
 	enum vm_mem_backing_src_type backing_src;
+	int slots;
 };
 
+static void toggle_dirty_logging(struct kvm_vm *vm, int slots, bool enable)
+{
+	int i;
+
+	for (i = 0; i < slots; i++) {
+		int slot = PERF_TEST_MEM_SLOT_INDEX + i;
+		int flags = enable ? KVM_MEM_LOG_DIRTY_PAGES : 0;
+
+		vm_mem_region_set_flags(vm, slot, flags);
+	}
+}
+
+static inline void enable_dirty_logging(struct kvm_vm *vm, int slots)
+{
+	toggle_dirty_logging(vm, slots, true);
+}
+
+static inline void disable_dirty_logging(struct kvm_vm *vm, int slots)
+{
+	toggle_dirty_logging(vm, slots, false);
+}
+
+static void get_dirty_log(struct kvm_vm *vm, int slots, unsigned long *bitmap,
+			  uint64_t nr_pages)
+{
+	uint64_t slot_pages = nr_pages / slots;
+	int i;
+
+	for (i = 0; i < slots; i++) {
+		int slot = PERF_TEST_MEM_SLOT_INDEX + i;
+		unsigned long *slot_bitmap = bitmap + i * slot_pages;
+
+		kvm_vm_get_dirty_log(vm, slot, slot_bitmap);
+	}
+}
+
+static void clear_dirty_log(struct kvm_vm *vm, int slots, unsigned long *bitmap,
+			    uint64_t nr_pages)
+{
+	uint64_t slot_pages = nr_pages / slots;
+	int i;
+
+	for (i = 0; i < slots; i++) {
+		int slot = PERF_TEST_MEM_SLOT_INDEX + i;
+		unsigned long *slot_bitmap = bitmap + i * slot_pages;
+
+		kvm_vm_clear_dirty_log(vm, slot, slot_bitmap, 0, slot_pages);
+	}
+}
+
 static void run_test(enum vm_guest_mode mode, void *arg)
 {
 	struct test_params *p = arg;
@@ -114,7 +165,7 @@ static void run_test(enum vm_guest_mode mode, void *arg)
 	struct timespec clear_dirty_log_total = (struct timespec){0};
 
 	vm = perf_test_create_vm(mode, nr_vcpus, guest_percpu_mem_size,
-				 p->backing_src);
+				 p->slots, p->backing_src);
 
 	perf_test_args.wr_fract = p->wr_fract;
 
@@ -163,8 +214,7 @@ static void run_test(enum vm_guest_mode mode, void *arg)
 
 	/* Enable dirty logging */
 	clock_gettime(CLOCK_MONOTONIC, &start);
-	vm_mem_region_set_flags(vm, PERF_TEST_MEM_SLOT_INDEX,
-				KVM_MEM_LOG_DIRTY_PAGES);
+	enable_dirty_logging(vm, p->slots);
 	ts_diff = timespec_elapsed(start);
 	pr_info("Enabling dirty logging time: %ld.%.9lds\n\n",
 		ts_diff.tv_sec, ts_diff.tv_nsec);
@@ -190,8 +240,7 @@ static void run_test(enum vm_guest_mode mode, void *arg)
 			iteration, ts_diff.tv_sec, ts_diff.tv_nsec);
 
 		clock_gettime(CLOCK_MONOTONIC, &start);
-		kvm_vm_get_dirty_log(vm, PERF_TEST_MEM_SLOT_INDEX, bmap);
-
+		get_dirty_log(vm, p->slots, bmap, host_num_pages);
 		ts_diff = timespec_elapsed(start);
 		get_dirty_log_total = timespec_add(get_dirty_log_total,
 						   ts_diff);
@@ -200,9 +249,7 @@ static void run_test(enum vm_guest_mode mode, void *arg)
 
 		if (dirty_log_manual_caps) {
 			clock_gettime(CLOCK_MONOTONIC, &start);
-			kvm_vm_clear_dirty_log(vm, PERF_TEST_MEM_SLOT_INDEX, bmap, 0,
-					       host_num_pages);
-
+			clear_dirty_log(vm, p->slots, bmap, host_num_pages);
 			ts_diff = timespec_elapsed(start);
 			clear_dirty_log_total = timespec_add(clear_dirty_log_total,
 							     ts_diff);
@@ -213,7 +260,7 @@ static void run_test(enum vm_guest_mode mode, void *arg)
 
 	/* Disable dirty logging */
 	clock_gettime(CLOCK_MONOTONIC, &start);
-	vm_mem_region_set_flags(vm, PERF_TEST_MEM_SLOT_INDEX, 0);
+	disable_dirty_logging(vm, p->slots);
 	ts_diff = timespec_elapsed(start);
 	pr_info("Disabling dirty logging time: %ld.%.9lds\n",
 		ts_diff.tv_sec, ts_diff.tv_nsec);
@@ -244,7 +291,8 @@ static void help(char *name)
 {
 	puts("");
 	printf("usage: %s [-h] [-i iterations] [-p offset] "
-	       "[-m mode] [-b vcpu bytes] [-v vcpus] [-o] [-s mem type]\n", name);
+	       "[-m mode] [-b vcpu bytes] [-v vcpus] [-o] [-s mem type]"
+	       "[-x memslots]\n", name);
 	puts("");
 	printf(" -i: specify iteration counts (default: %"PRIu64")\n",
 	       TEST_HOST_LOOP_N);
@@ -263,6 +311,8 @@ static void help(char *name)
 	       "     them into a separate region of memory for each vCPU.\n");
 	printf(" -s: specify the type of memory that should be used to\n"
 	       "     back the guest data region.\n\n");
+	printf(" -x: Split the memory region into this number of memslots.\n"
+	       "     (default: 1)");
 	backing_src_help();
 	puts("");
 	exit(0);
@@ -276,6 +326,7 @@ int main(int argc, char *argv[])
 		.wr_fract = 1,
 		.partition_vcpu_memory_access = true,
 		.backing_src = VM_MEM_SRC_ANONYMOUS,
+		.slots = 1,
 	};
 	int opt;
 
@@ -286,7 +337,7 @@ int main(int argc, char *argv[])
 
 	guest_modes_append_default();
 
-	while ((opt = getopt(argc, argv, "hi:p:m:b:f:v:os:")) != -1) {
+	while ((opt = getopt(argc, argv, "hi:p:m:b:f:v:os:x:")) != -1) {
 		switch (opt) {
 		case 'i':
 			p.iterations = atoi(optarg);
@@ -316,6 +367,9 @@ int main(int argc, char *argv[])
 		case 's':
 			p.backing_src = parse_backing_src_type(optarg);
 			break;
+		case 'x':
+			p.slots = atoi(optarg);
+			break;
 		case 'h':
 		default:
 			help(argv[0]);