linux/tools/testing/selftests/resctrl/cache.c

// SPDX-License-Identifier: GPL-2.0

#include <stdint.h>
#include "resctrl.h"

struct read_format {
	__u64 nr;			/* The number of events */
	struct {
		__u64 value;		/* The value of the event */
	} values[2];
};

static struct perf_event_attr pea_llc_miss;
static struct read_format rf_cqm;
static int fd_lm;
char llc_occup_path[1024];

static void initialize_perf_event_attr(void)
{
	pea_llc_miss.type = PERF_TYPE_HARDWARE;
	pea_llc_miss.size = sizeof(struct perf_event_attr);
	pea_llc_miss.read_format = PERF_FORMAT_GROUP;
	pea_llc_miss.exclude_kernel = 1;
	pea_llc_miss.exclude_hv = 1;
	pea_llc_miss.exclude_idle = 1;
	pea_llc_miss.exclude_callchain_kernel = 1;
	pea_llc_miss.inherit = 1;
	pea_llc_miss.exclude_guest = 1;
	pea_llc_miss.disabled = 1;
}

static void ioctl_perf_event_ioc_reset_enable(void)
{
	ioctl(fd_lm, PERF_EVENT_IOC_RESET, 0);
	ioctl(fd_lm, PERF_EVENT_IOC_ENABLE, 0);
}

static int perf_event_open_llc_miss(pid_t pid, int cpu_no)
{
	fd_lm = perf_event_open(&pea_llc_miss, pid, cpu_no, -1,
				PERF_FLAG_FD_CLOEXEC);
	if (fd_lm == -1) {
		ksft_perror("Error opening leader");
		return -1;
	}

	return 0;
}

static void initialize_llc_perf(void)
{
	memset(&pea_llc_miss, 0, sizeof(struct perf_event_attr));
	memset(&rf_cqm, 0, sizeof(struct read_format));

	/* Initialize perf_event_attr structures for HW_CACHE_MISSES */
	initialize_perf_event_attr();

	pea_llc_miss.config = PERF_COUNT_HW_CACHE_MISSES;

	rf_cqm.nr = 1;
}

static int reset_enable_llc_perf(pid_t pid, int cpu_no)
{
	int ret = 0;

	ret = perf_event_open_llc_miss(pid, cpu_no);
	if (ret < 0)
		return ret;

	/* Start counters to log values */
	ioctl_perf_event_ioc_reset_enable();

	return 0;
}

/*
 * get_llc_perf:	llc cache miss through perf events
 * @llc_perf_miss:	LLC miss counter that is filled on success
 *
 * Perf events like HW_CACHE_MISSES could be used to validate number of
 * cache lines allocated.
 *
 * Return: =0 on success.  <0 on failure.
 */
static int get_llc_perf(__u64 *llc_perf_miss)
{
	int ret;

	/* Stop counters after one span to get miss rate */

	ioctl(fd_lm, PERF_EVENT_IOC_DISABLE, 0);

	ret = read(fd_lm, &rf_cqm, sizeof(struct read_format));
	if (ret == -1) {
		ksft_perror("Could not get llc misses through perf");
		return -1;
	}

	*llc_perf_miss = rf_cqm.values[0].value;

	return 0;
}

/*
 * Get LLC Occupancy as reported by RESCTRL FS
 * For CMT,
 * 1. If con_mon grp and mon grp given, then read from mon grp in
 * con_mon grp
 * 2. If only con_mon grp given, then read from con_mon grp
 * 3. If both not given, then read from root con_mon grp
 * For CAT,
 * 1. If con_mon grp given, then read from it
 * 2. If con_mon grp not given, then read from root con_mon grp
 *
 * Return: =0 on success.  <0 on failure.
 */
static int get_llc_occu_resctrl(unsigned long *llc_occupancy)
{
	FILE *fp;

	fp = fopen(llc_occup_path, "r");
	if (!fp) {
		ksft_perror("Failed to open results file");

		return -1;
	}
	if (fscanf(fp, "%lu", llc_occupancy) <= 0) {
		ksft_perror("Could not get llc occupancy");
		fclose(fp);

		return -1;
	}
	fclose(fp);

	return 0;
}

/*
 * print_results_cache:	the cache results are stored in a file
 * @filename:		file that stores the results
 * @bm_pid:		child pid that runs benchmark
 * @llc_value:		perf miss value /
 *			llc occupancy value reported by resctrl FS
 *
 * Return:		0 on success, < 0 on error.
 */
static int print_results_cache(const char *filename, int bm_pid, __u64 llc_value)
{
	FILE *fp;

	if (strcmp(filename, "stdio") == 0 || strcmp(filename, "stderr") == 0) {
		printf("Pid: %d \t LLC_value: %llu\n", bm_pid, llc_value);
	} else {
		fp = fopen(filename, "a");
		if (!fp) {
			ksft_perror("Cannot open results file");

			return -1;
		}
		fprintf(fp, "Pid: %d \t llc_value: %llu\n", bm_pid, llc_value);
		fclose(fp);
	}

	return 0;
}

/*
 * perf_event_measure - Measure perf events
 * @filename:	Filename for writing the results
 * @bm_pid:	PID that runs the benchmark
 *
 * Measures perf events (e.g., cache misses) and writes the results into
 * @filename. @bm_pid is written to the results file along with the measured
 * value.
 *
 * Return: =0 on success. <0 on failure.
 */
static int perf_event_measure(const char *filename, int bm_pid)
{
	__u64 llc_perf_miss = 0;
	int ret;

	ret = get_llc_perf(&llc_perf_miss);
	if (ret < 0)
		return ret;

	return print_results_cache(filename, bm_pid, llc_perf_miss);
}

/*
 * measure_llc_resctrl - Measure resctrl LLC value from resctrl
 * @filename:	Filename for writing the results
 * @bm_pid:	PID that runs the benchmark
 *
 * Measures LLC occupancy from resctrl and writes the results into @filename.
 * @bm_pid is written to the results file along with the measured value.
 *
 * Return: =0 on success. <0 on failure.
 */
int measure_llc_resctrl(const char *filename, int bm_pid)
{
	unsigned long llc_occu_resc = 0;
	int ret;

	ret = get_llc_occu_resctrl(&llc_occu_resc);
	if (ret < 0)
		return ret;

	return print_results_cache(filename, bm_pid, llc_occu_resc);
}

/*
 * cache_val:		execute benchmark and measure LLC occupancy resctrl
 * and perf cache miss for the benchmark
 * @param:		parameters passed to cache_val()
 * @span:		buffer size for the benchmark
 *
 * Return:		0 when the test was run, < 0 on error.
 */
int cat_val(struct resctrl_val_param *param, size_t span)
{
	int memflush = 1, operation = 0, ret = 0;
	char *resctrl_val = param->resctrl_val;
	pid_t bm_pid;

	if (strcmp(param->filename, "") == 0)
		sprintf(param->filename, "stdio");

	bm_pid = getpid();

	/* Taskset benchmark to specified cpu */
	ret = taskset_benchmark(bm_pid, param->cpu_no);
	if (ret)
		return ret;

	/* Write benchmark to specified con_mon grp, mon_grp in resctrl FS*/
	ret = write_bm_pid_to_resctrl(bm_pid, param->ctrlgrp, param->mongrp,
				      resctrl_val);
	if (ret)
		return ret;

	initialize_llc_perf();

	/* Test runs until the callback setup() tells the test to stop. */
	while (1) {
		ret = param->setup(param);
		if (ret == END_OF_TESTS) {
			ret = 0;
			break;
		}
		if (ret < 0)
			break;
		ret = reset_enable_llc_perf(bm_pid, param->cpu_no);
		if (ret)
			break;

		if (run_fill_buf(span, memflush, operation, true)) {
			fprintf(stderr, "Error-running fill buffer\n");
			ret = -1;
			goto pe_close;
		}

		sleep(1);
		ret = perf_event_measure(param->filename, bm_pid);
		if (ret)
			goto pe_close;
	}

	return ret;

pe_close:
	close(fd_lm);
	return ret;
}

/*
 * show_cache_info - Show generic cache test information
 * @no_of_bits:		Number of bits
 * @avg_llc_val:	Average of LLC cache result data
 * @cache_span:		Cache span
 * @lines:		@cache_span in lines or bytes
 */
void show_cache_info(int no_of_bits, __u64 avg_llc_val, size_t cache_span, bool lines)
{
	ksft_print_msg("Number of bits: %d\n", no_of_bits);
	ksft_print_msg("Average LLC val: %llu\n", avg_llc_val);
	ksft_print_msg("Cache span (%s): %zu\n", lines ? "lines" : "bytes",
		       cache_span);
}