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

// SPDX-License-Identifier: GPL-2.0
/*
 * Cache Allocation Technology (CAT) test
 *
 * Copyright (C) 2018 Intel Corporation
 *
 * Authors:
 *    Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>,
 *    Fenghua Yu <fenghua.yu@intel.com>
 */
#include "resctrl.h"
#include <unistd.h>

#define RESULT_FILE_NAME1	"result_cat1"
#define RESULT_FILE_NAME2	"result_cat2"
#define NUM_OF_RUNS		5
#define MAX_DIFF_PERCENT	4
#define MAX_DIFF		1000000

/*
 * Change schemata. Write schemata to specified
 * con_mon grp, mon_grp in resctrl FS.
 * Run 5 times in order to get average values.
 */
static int cat_setup(struct resctrl_val_param *p)
{
	char schemata[64];
	int ret = 0;

	/* Run NUM_OF_RUNS times */
	if (p->num_of_runs >= NUM_OF_RUNS)
		return END_OF_TESTS;

	if (p->num_of_runs == 0) {
		sprintf(schemata, "%lx", p->mask);
		ret = write_schemata(p->ctrlgrp, schemata, p->cpu_no,
				     p->resctrl_val);
	}
	p->num_of_runs++;

	return ret;
}

static int show_results_info(__u64 sum_llc_val, int no_of_bits,
			     unsigned long cache_span, unsigned long max_diff,
			     unsigned long max_diff_percent, unsigned long num_of_runs,
			     bool platform)
{
	__u64 avg_llc_val = 0;
	float diff_percent;
	int ret;

	avg_llc_val = sum_llc_val / num_of_runs;
	diff_percent = ((float)cache_span - avg_llc_val) / cache_span * 100;

	ret = platform && abs((int)diff_percent) > max_diff_percent;

	ksft_print_msg("%s Check cache miss rate within %lu%%\n",
		       ret ? "Fail:" : "Pass:", max_diff_percent);

	ksft_print_msg("Percent diff=%d\n", abs((int)diff_percent));

	show_cache_info(no_of_bits, avg_llc_val, cache_span, true);

	return ret;
}

static int check_results(struct resctrl_val_param *param, size_t span)
{
	char *token_array[8], temp[512];
	int runs = 0, no_of_bits = 0;
	__u64 sum_llc_perf_miss = 0;
	FILE *fp;

	ksft_print_msg("Checking for pass/fail\n");
	fp = fopen(param->filename, "r");
	if (!fp) {
		ksft_perror("Cannot open file");

		return -1;
	}

	while (fgets(temp, sizeof(temp), fp)) {
		char *token = strtok(temp, ":\t");
		int fields = 0;

		while (token) {
			token_array[fields++] = token;
			token = strtok(NULL, ":\t");
		}
		/*
		 * Discard the first value which is inaccurate due to monitoring
		 * setup transition phase.
		 */
		if (runs > 0)
			sum_llc_perf_miss += strtoull(token_array[3], NULL, 0);
		runs++;
	}

	fclose(fp);
	no_of_bits = count_bits(param->mask);

	return show_results_info(sum_llc_perf_miss, no_of_bits, span / 64,
				 MAX_DIFF, MAX_DIFF_PERCENT, runs - 1,
				 get_vendor() == ARCH_INTEL);
}

void cat_test_cleanup(void)
{
	remove(RESULT_FILE_NAME1);
	remove(RESULT_FILE_NAME2);
}

/*
 * cat_test - Execute CAT benchmark and measure cache misses
 * @param:		Parameters passed to cat_test()
 * @span:		Buffer size for the benchmark
 *
 * Return:		0 when the test was run, < 0 on error.
 */
static int cat_test(struct resctrl_val_param *param, size_t span)
{
	int memflush = 1, operation = 0, ret = 0;
	char *resctrl_val = param->resctrl_val;
	struct perf_event_read pe_read;
	struct perf_event_attr pea;
	pid_t bm_pid;
	int pe_fd;

	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;

	perf_event_attr_initialize(&pea, PERF_COUNT_HW_CACHE_MISSES);
	perf_event_initialize_read_format(&pe_read);
	pe_fd = perf_open(&pea, bm_pid, param->cpu_no);
	if (pe_fd < 0)
		return pe_fd;

	/* 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 = perf_event_reset_enable(pe_fd);
		if (ret)
			goto pe_close;

		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(pe_fd, &pe_read, param->filename, bm_pid);
		if (ret)
			goto pe_close;
	}

	return ret;

pe_close:
	close(pe_fd);
	return ret;
}

int cat_perf_miss_val(int cpu_no, int n, char *cache_type)
{
	unsigned long full_cache_mask, long_mask;
	unsigned long l_mask, l_mask_1;
	int ret, pipefd[2], sibling_cpu_no;
	unsigned long cache_total_size = 0;
	int count_of_bits;
	char pipe_message;
	size_t span;

	ret = get_full_cbm(cache_type, &full_cache_mask);
	if (ret)
		return ret;
	/* Get the largest contiguous exclusive portion of the cache */
	ret = get_mask_no_shareable(cache_type, &long_mask);
	if (ret)
		return ret;

	/* Get L3/L2 cache size */
	ret = get_cache_size(cpu_no, cache_type, &cache_total_size);
	if (ret)
		return ret;
	ksft_print_msg("Cache size :%lu\n", cache_total_size);

	count_of_bits = count_bits(long_mask);

	if (!n)
		n = count_of_bits / 2;

	if (n > count_of_bits - 1) {
		ksft_print_msg("Invalid input value for no_of_bits n!\n");
		ksft_print_msg("Please enter value in range 1 to %d\n",
			       count_of_bits - 1);
		return -1;
	}

	/* Get core id from same socket for running another thread */
	sibling_cpu_no = get_core_sibling(cpu_no);
	if (sibling_cpu_no < 0)
		return -1;

	struct resctrl_val_param param = {
		.resctrl_val	= CAT_STR,
		.cpu_no		= cpu_no,
		.setup		= cat_setup,
	};

	l_mask = long_mask >> n;
	l_mask_1 = ~l_mask & long_mask;

	/* Set param values for parent thread which will be allocated bitmask
	 * with (max_bits - n) bits
	 */
	span = cache_portion_size(cache_total_size, l_mask, full_cache_mask);
	strcpy(param.ctrlgrp, "c2");
	strcpy(param.mongrp, "m2");
	strcpy(param.filename, RESULT_FILE_NAME2);
	param.mask = l_mask;
	param.num_of_runs = 0;

	if (pipe(pipefd)) {
		ksft_perror("Unable to create pipe");
		return -1;
	}

	fflush(stdout);
	bm_pid = fork();

	/* Set param values for child thread which will be allocated bitmask
	 * with n bits
	 */
	if (bm_pid == 0) {
		param.mask = l_mask_1;
		strcpy(param.ctrlgrp, "c1");
		strcpy(param.mongrp, "m1");
		span = cache_portion_size(cache_total_size, l_mask_1, full_cache_mask);
		strcpy(param.filename, RESULT_FILE_NAME1);
		param.num_of_runs = 0;
		param.cpu_no = sibling_cpu_no;
	}

	remove(param.filename);

	ret = cat_test(&param, span);
	if (ret == 0)
		ret = check_results(&param, span);

	if (bm_pid == 0) {
		/* Tell parent that child is ready */
		close(pipefd[0]);
		pipe_message = 1;
		if (write(pipefd[1], &pipe_message, sizeof(pipe_message)) <
		    sizeof(pipe_message))
			/*
			 * Just print the error message.
			 * Let while(1) run and wait for itself to be killed.
			 */
			ksft_perror("Failed signaling parent process");

		close(pipefd[1]);
		while (1)
			;
	} else {
		/* Parent waits for child to be ready. */
		close(pipefd[1]);
		pipe_message = 0;
		while (pipe_message != 1) {
			if (read(pipefd[0], &pipe_message,
				 sizeof(pipe_message)) < sizeof(pipe_message)) {
				ksft_perror("Failed reading from child process");
				break;
			}
		}
		close(pipefd[0]);
		kill(bm_pid, SIGKILL);
	}

	cat_test_cleanup();

	return ret;
}