dirty_log_perf_test.c

  1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * KVM dirty page logging performance test
  4 *
  5 * Based on dirty_log_test.c
  6 *
  7 * Copyright (C) 2018, Red Hat, Inc.
  8 * Copyright (C) 2020, Google, Inc.
  9 */
 10
 11#include <stdio.h>
 12#include <stdlib.h>
 13#include <time.h>
 14#include <pthread.h>
 15#include <linux/bitmap.h>
 16
 17#include "kvm_util.h"
 18#include "test_util.h"
 19#include "memstress.h"
 20#include "guest_modes.h"
 21#include "ucall_common.h"
 22
 23/* How many host loops to run by default (one KVM_GET_DIRTY_LOG for each loop)*/
 24#define TEST_HOST_LOOP_N		2UL
 25
 26static int nr_vcpus = 1;
 27static uint64_t guest_percpu_mem_size = DEFAULT_PER_VCPU_MEM_SIZE;
 28static bool run_vcpus_while_disabling_dirty_logging;
 29
 30/* Host variables */
 31static u64 dirty_log_manual_caps;
 32static bool host_quit;
 33static int iteration;
 34static int vcpu_last_completed_iteration[KVM_MAX_VCPUS];
 35
 36static void vcpu_worker(struct memstress_vcpu_args *vcpu_args)
 37{
 38	struct kvm_vcpu *vcpu = vcpu_args->vcpu;
 39	int vcpu_idx = vcpu_args->vcpu_idx;
 40	uint64_t pages_count = 0;
 41	struct kvm_run *run;
 42	struct timespec start;
 43	struct timespec ts_diff;
 44	struct timespec total = (struct timespec){0};
 45	struct timespec avg;
 46	int ret;
 47
 48	run = vcpu->run;
 49
 50	while (!READ_ONCE(host_quit)) {
 51		int current_iteration = READ_ONCE(iteration);
 52
 53		clock_gettime(CLOCK_MONOTONIC, &start);
 54		ret = _vcpu_run(vcpu);
 55		ts_diff = timespec_elapsed(start);
 56
 57		TEST_ASSERT(ret == 0, "vcpu_run failed: %d", ret);
 58		TEST_ASSERT(get_ucall(vcpu, NULL) == UCALL_SYNC,
 59			    "Invalid guest sync status: exit_reason=%s",
 60			    exit_reason_str(run->exit_reason));
 61
 62		pr_debug("Got sync event from vCPU %d\n", vcpu_idx);
 63		vcpu_last_completed_iteration[vcpu_idx] = current_iteration;
 64		pr_debug("vCPU %d updated last completed iteration to %d\n",
 65			 vcpu_idx, vcpu_last_completed_iteration[vcpu_idx]);
 66
 67		if (current_iteration) {
 68			pages_count += vcpu_args->pages;
 69			total = timespec_add(total, ts_diff);
 70			pr_debug("vCPU %d iteration %d dirty memory time: %ld.%.9lds\n",
 71				vcpu_idx, current_iteration, ts_diff.tv_sec,
 72				ts_diff.tv_nsec);
 73		} else {
 74			pr_debug("vCPU %d iteration %d populate memory time: %ld.%.9lds\n",
 75				vcpu_idx, current_iteration, ts_diff.tv_sec,
 76				ts_diff.tv_nsec);
 77		}
 78
 79		/*
 80		 * Keep running the guest while dirty logging is being disabled
 81		 * (iteration is negative) so that vCPUs are accessing memory
 82		 * for the entire duration of zapping collapsible SPTEs.
 83		 */
 84		while (current_iteration == READ_ONCE(iteration) &&
 85		       READ_ONCE(iteration) >= 0 && !READ_ONCE(host_quit)) {}
 86	}
 87
 88	avg = timespec_div(total, vcpu_last_completed_iteration[vcpu_idx]);
 89	pr_debug("\nvCPU %d dirtied 0x%lx pages over %d iterations in %ld.%.9lds. (Avg %ld.%.9lds/iteration)\n",
 90		vcpu_idx, pages_count, vcpu_last_completed_iteration[vcpu_idx],
 91		total.tv_sec, total.tv_nsec, avg.tv_sec, avg.tv_nsec);
 92}
 93
 94struct test_params {
 95	unsigned long iterations;
 96	uint64_t phys_offset;
 97	bool partition_vcpu_memory_access;
 98	enum vm_mem_backing_src_type backing_src;
 99	int slots;
100	uint32_t write_percent;
101	bool random_access;
102};
103
104static void run_test(enum vm_guest_mode mode, void *arg)
105{
106	struct test_params *p = arg;
107	struct kvm_vm *vm;
108	unsigned long **bitmaps;
109	uint64_t guest_num_pages;
110	uint64_t host_num_pages;
111	uint64_t pages_per_slot;
112	struct timespec start;
113	struct timespec ts_diff;
114	struct timespec get_dirty_log_total = (struct timespec){0};
115	struct timespec vcpu_dirty_total = (struct timespec){0};
116	struct timespec avg;
117	struct timespec clear_dirty_log_total = (struct timespec){0};
118	int i;
119
120	vm = memstress_create_vm(mode, nr_vcpus, guest_percpu_mem_size,
121				 p->slots, p->backing_src,
122				 p->partition_vcpu_memory_access);
123
124	memstress_set_write_percent(vm, p->write_percent);
125
126	guest_num_pages = (nr_vcpus * guest_percpu_mem_size) >> vm->page_shift;
127	guest_num_pages = vm_adjust_num_guest_pages(mode, guest_num_pages);
128	host_num_pages = vm_num_host_pages(mode, guest_num_pages);
129	pages_per_slot = host_num_pages / p->slots;
130
131	bitmaps = memstress_alloc_bitmaps(p->slots, pages_per_slot);
132
133	if (dirty_log_manual_caps)
134		vm_enable_cap(vm, KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2,
135			      dirty_log_manual_caps);
136
137	/* Start the iterations */
138	iteration = 0;
139	host_quit = false;
140
141	clock_gettime(CLOCK_MONOTONIC, &start);
142	for (i = 0; i < nr_vcpus; i++)
143		vcpu_last_completed_iteration[i] = -1;
144
145	/*
146	 * Use 100% writes during the population phase to ensure all
147	 * memory is actually populated and not just mapped to the zero
148	 * page. The prevents expensive copy-on-write faults from
149	 * occurring during the dirty memory iterations below, which
150	 * would pollute the performance results.
151	 */
152	memstress_set_write_percent(vm, 100);
153	memstress_set_random_access(vm, false);
154	memstress_start_vcpu_threads(nr_vcpus, vcpu_worker);
155
156	/* Allow the vCPUs to populate memory */
157	pr_debug("Starting iteration %d - Populating\n", iteration);
158	for (i = 0; i < nr_vcpus; i++) {
159		while (READ_ONCE(vcpu_last_completed_iteration[i]) !=
160		       iteration)
161			;
162	}
163
164	ts_diff = timespec_elapsed(start);
165	pr_info("Populate memory time: %ld.%.9lds\n",
166		ts_diff.tv_sec, ts_diff.tv_nsec);
167
168	/* Enable dirty logging */
169	clock_gettime(CLOCK_MONOTONIC, &start);
170	memstress_enable_dirty_logging(vm, p->slots);
171	ts_diff = timespec_elapsed(start);
172	pr_info("Enabling dirty logging time: %ld.%.9lds\n\n",
173		ts_diff.tv_sec, ts_diff.tv_nsec);
174
175	memstress_set_write_percent(vm, p->write_percent);
176	memstress_set_random_access(vm, p->random_access);
177
178	while (iteration < p->iterations) {
179		/*
180		 * Incrementing the iteration number will start the vCPUs
181		 * dirtying memory again.
182		 */
183		clock_gettime(CLOCK_MONOTONIC, &start);
184		iteration++;
185
186		pr_debug("Starting iteration %d\n", iteration);
187		for (i = 0; i < nr_vcpus; i++) {
188			while (READ_ONCE(vcpu_last_completed_iteration[i])
189			       != iteration)
190				;
191		}
192
193		ts_diff = timespec_elapsed(start);
194		vcpu_dirty_total = timespec_add(vcpu_dirty_total, ts_diff);
195		pr_info("Iteration %d dirty memory time: %ld.%.9lds\n",
196			iteration, ts_diff.tv_sec, ts_diff.tv_nsec);
197
198		clock_gettime(CLOCK_MONOTONIC, &start);
199		memstress_get_dirty_log(vm, bitmaps, p->slots);
200		ts_diff = timespec_elapsed(start);
201		get_dirty_log_total = timespec_add(get_dirty_log_total,
202						   ts_diff);
203		pr_info("Iteration %d get dirty log time: %ld.%.9lds\n",
204			iteration, ts_diff.tv_sec, ts_diff.tv_nsec);
205
206		if (dirty_log_manual_caps) {
207			clock_gettime(CLOCK_MONOTONIC, &start);
208			memstress_clear_dirty_log(vm, bitmaps, p->slots,
209						  pages_per_slot);
210			ts_diff = timespec_elapsed(start);
211			clear_dirty_log_total = timespec_add(clear_dirty_log_total,
212							     ts_diff);
213			pr_info("Iteration %d clear dirty log time: %ld.%.9lds\n",
214				iteration, ts_diff.tv_sec, ts_diff.tv_nsec);
215		}
216	}
217
218	/*
219	 * Run vCPUs while dirty logging is being disabled to stress disabling
220	 * in terms of both performance and correctness.  Opt-in via command
221	 * line as this significantly increases time to disable dirty logging.
222	 */
223	if (run_vcpus_while_disabling_dirty_logging)
224		WRITE_ONCE(iteration, -1);
225
226	/* Disable dirty logging */
227	clock_gettime(CLOCK_MONOTONIC, &start);
228	memstress_disable_dirty_logging(vm, p->slots);
229	ts_diff = timespec_elapsed(start);
230	pr_info("Disabling dirty logging time: %ld.%.9lds\n",
231		ts_diff.tv_sec, ts_diff.tv_nsec);
232
233	/*
234	 * Tell the vCPU threads to quit.  No need to manually check that vCPUs
235	 * have stopped running after disabling dirty logging, the join will
236	 * wait for them to exit.
237	 */
238	host_quit = true;
239	memstress_join_vcpu_threads(nr_vcpus);
240
241	avg = timespec_div(get_dirty_log_total, p->iterations);
242	pr_info("Get dirty log over %lu iterations took %ld.%.9lds. (Avg %ld.%.9lds/iteration)\n",
243		p->iterations, get_dirty_log_total.tv_sec,
244		get_dirty_log_total.tv_nsec, avg.tv_sec, avg.tv_nsec);
245
246	if (dirty_log_manual_caps) {
247		avg = timespec_div(clear_dirty_log_total, p->iterations);
248		pr_info("Clear dirty log over %lu iterations took %ld.%.9lds. (Avg %ld.%.9lds/iteration)\n",
249			p->iterations, clear_dirty_log_total.tv_sec,
250			clear_dirty_log_total.tv_nsec, avg.tv_sec, avg.tv_nsec);
251	}
252
253	memstress_free_bitmaps(bitmaps, p->slots);
254	memstress_destroy_vm(vm);
255}
256
257static void help(char *name)
258{
259	puts("");
260	printf("usage: %s [-h] [-a] [-i iterations] [-p offset] [-g] "
261	       "[-m mode] [-n] [-b vcpu bytes] [-v vcpus] [-o] [-r random seed ] [-s mem type]"
262	       "[-x memslots] [-w percentage] [-c physical cpus to run test on]\n", name);
263	puts("");
264	printf(" -a: access memory randomly rather than in order.\n");
265	printf(" -i: specify iteration counts (default: %"PRIu64")\n",
266	       TEST_HOST_LOOP_N);
267	printf(" -g: Do not enable KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2. This\n"
268	       "     makes KVM_GET_DIRTY_LOG clear the dirty log (i.e.\n"
269	       "     KVM_DIRTY_LOG_MANUAL_PROTECT_ENABLE is not enabled)\n"
270	       "     and writes will be tracked as soon as dirty logging is\n"
271	       "     enabled on the memslot (i.e. KVM_DIRTY_LOG_INITIALLY_SET\n"
272	       "     is not enabled).\n");
273	printf(" -p: specify guest physical test memory offset\n"
274	       "     Warning: a low offset can conflict with the loaded test code.\n");
275	guest_modes_help();
276	printf(" -n: Run the vCPUs in nested mode (L2)\n");
277	printf(" -e: Run vCPUs while dirty logging is being disabled.  This\n"
278	       "     can significantly increase runtime, especially if there\n"
279	       "     isn't a dedicated pCPU for the main thread.\n");
280	printf(" -b: specify the size of the memory region which should be\n"
281	       "     dirtied by each vCPU. e.g. 10M or 3G.\n"
282	       "     (default: 1G)\n");
283	printf(" -v: specify the number of vCPUs to run.\n");
284	printf(" -o: Overlap guest memory accesses instead of partitioning\n"
285	       "     them into a separate region of memory for each vCPU.\n");
286	printf(" -r: specify the starting random seed.\n");
287	backing_src_help("-s");
288	printf(" -x: Split the memory region into this number of memslots.\n"
289	       "     (default: 1)\n");
290	printf(" -w: specify the percentage of pages which should be written to\n"
291	       "     as an integer from 0-100 inclusive. This is probabilistic,\n"
292	       "     so -w X means each page has an X%% chance of writing\n"
293	       "     and a (100-X)%% chance of reading.\n"
294	       "     (default: 100 i.e. all pages are written to.)\n");
295	kvm_print_vcpu_pinning_help();
296	puts("");
297	exit(0);
298}
299
300int main(int argc, char *argv[])
301{
302	int max_vcpus = kvm_check_cap(KVM_CAP_MAX_VCPUS);
303	const char *pcpu_list = NULL;
304	struct test_params p = {
305		.iterations = TEST_HOST_LOOP_N,
306		.partition_vcpu_memory_access = true,
307		.backing_src = DEFAULT_VM_MEM_SRC,
308		.slots = 1,
309		.write_percent = 100,
310	};
311	int opt;
312
313	/* Override the seed to be deterministic by default. */
314	guest_random_seed = 1;
315
316	dirty_log_manual_caps =
317		kvm_check_cap(KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2);
318	dirty_log_manual_caps &= (KVM_DIRTY_LOG_MANUAL_PROTECT_ENABLE |
319				  KVM_DIRTY_LOG_INITIALLY_SET);
320
321	guest_modes_append_default();
322
323	while ((opt = getopt(argc, argv, "ab:c:eghi:m:nop:r:s:v:x:w:")) != -1) {
324		switch (opt) {
325		case 'a':
326			p.random_access = true;
327			break;
328		case 'b':
329			guest_percpu_mem_size = parse_size(optarg);
330			break;
331		case 'c':
332			pcpu_list = optarg;
333			break;
334		case 'e':
335			/* 'e' is for evil. */
336			run_vcpus_while_disabling_dirty_logging = true;
337			break;
338		case 'g':
339			dirty_log_manual_caps = 0;
340			break;
341		case 'h':
342			help(argv[0]);
343			break;
344		case 'i':
345			p.iterations = atoi_positive("Number of iterations", optarg);
346			break;
347		case 'm':
348			guest_modes_cmdline(optarg);
349			break;
350		case 'n':
351			memstress_args.nested = true;
352			break;
353		case 'o':
354			p.partition_vcpu_memory_access = false;
355			break;
356		case 'p':
357			p.phys_offset = strtoull(optarg, NULL, 0);
358			break;
359		case 'r':
360			guest_random_seed = atoi_positive("Random seed", optarg);
361			break;
362		case 's':
363			p.backing_src = parse_backing_src_type(optarg);
364			break;
365		case 'v':
366			nr_vcpus = atoi_positive("Number of vCPUs", optarg);
367			TEST_ASSERT(nr_vcpus <= max_vcpus,
368				    "Invalid number of vcpus, must be between 1 and %d", max_vcpus);
369			break;
370		case 'w':
371			p.write_percent = atoi_non_negative("Write percentage", optarg);
372			TEST_ASSERT(p.write_percent <= 100,
373				    "Write percentage must be between 0 and 100");
374			break;
375		case 'x':
376			p.slots = atoi_positive("Number of slots", optarg);
377			break;
378		default:
379			help(argv[0]);
380			break;
381		}
382	}
383
384	if (pcpu_list) {
385		kvm_parse_vcpu_pinning(pcpu_list, memstress_args.vcpu_to_pcpu,
386				       nr_vcpus);
387		memstress_args.pin_vcpus = true;
388	}
389
390	TEST_ASSERT(p.iterations >= 2, "The test should have at least two iterations");
391
392	pr_info("Test iterations: %"PRIu64"\n",	p.iterations);
393
394	for_each_guest_mode(run_test, &p);
395
396	return 0;
397}