[PATCH v2 4/8] selftests/resctrl: Add callback to start a benchmark

[Fenghua Yu]

From: Sai Praneeth Prakhya <sai.praneeth.prakhya@xxxxxxxxx>

The callback starts a child process and puts the child pid in created
resctrl group with specified memory bandwidth in schemata. The child
starts running benchmark.

Signed-off-by: Sai Praneeth Prakhya <sai.praneeth.prakhya@xxxxxxxxx>
Signed-off-by: Arshiya Hayatkhan Pathan <arshiya.hayatkhan.pathan@xxxxxxxxx>
Signed-off-by: Fenghua Yu <fenghua.yu@xxxxxxxxx>
---
 tools/testing/selftests/resctrl/membw.c   | 273 ++++++++++++++++++++++++++++++
 tools/testing/selftests/resctrl/resctrl.h |  27 +++
 2 files changed, 300 insertions(+)

diff --git a/tools/testing/selftests/resctrl/membw.c b/tools/testing/selftests/resctrl/membw.c
index 1bced7e7f148..dfcd9c1244d8 100644
--- a/tools/testing/selftests/resctrl/membw.c
+++ b/tools/testing/selftests/resctrl/membw.c
@@ -401,3 +401,276 @@ static unsigned long get_mem_bw_resctrl(void)
 
 	return mbm_total;
 }
+
+pid_t bm_pid, ppid;
+
+static void ctrlc_handler(int signum, siginfo_t *info, void *ptr)
+{
+	kill(bm_pid, SIGKILL);
+	printf("Ending\n\n");
+
+	exit(EXIT_SUCCESS);
+}
+
+/*
+ * print_results_bw:	the memory bandwidth results are stored in a file
+ * @filename:		file that stores the results
+ * @bm_pid:		child pid that runs benchmark
+ * @bw_imc:		perf imc counter value
+ * @bw_resc:		memory bandwidth value
+ *
+ * Return:		0 on success. non-zero on failure.
+ */
+static int print_results_bw(char *filename,  int bm_pid, float bw_imc,
+			    unsigned long bw_resc)
+{
+	int diff = abs(bw_imc - bw_resc);
+	FILE *fp;
+
+	if (strcmp(filename, "stdio") == 0 || strcmp(filename, "stderr") == 0) {
+		printf("Pid: %d \t Mem_BW_iMC: %f \t ", bm_pid, bw_imc);
+		printf("Mem_BW_resc: %lu \t Difference: %d\n", bw_resc, diff);
+	} else {
+		fp = fopen(filename, "a");
+		if (!fp) {
+			perror("Cannot open results file");
+
+			return errno;
+		}
+		if (fprintf(fp, "Pid: %d \t Mem_BW_iMC: %f \t ",
+			    bm_pid, bw_imc) <= 0 ||
+		    fprintf(fp, "Mem_BW_resc: %lu \t Difference: %d\n",
+			    bw_resc, diff) <= 0) {
+			fclose(fp);
+			perror("Could not log results.");
+
+			return errno;
+		}
+		fclose(fp);
+	}
+
+	return 0;
+}
+
+static int
+measure_vals(struct resctrl_val_param *param, unsigned long *bw_resc_start)
+{
+	unsigned long bw_imc, bw_resc, bw_resc_end;
+	int ret;
+
+	/*
+	 * Measure memory bandwidth from resctrl and from
+	 * another source which is perf imc value or could
+	 * be something else if perf imc event is not available.
+	 * Compare the two values to validate resctrl value.
+	 * It takes 1sec to measure the data.
+	 */
+	bw_imc = get_mem_bw_imc(param->cpu_no, param->bw_report);
+	if (bw_imc < 0)
+		return bw_imc;
+
+	bw_resc_end = get_mem_bw_resctrl();
+	if (bw_resc_end < 0)
+		return bw_resc_end;
+
+	bw_resc = (bw_resc_end - *bw_resc_start) / MB;
+	ret = print_results_bw(param->filename, bm_pid, bw_imc, bw_resc);
+	if (ret)
+		return ret;
+
+	*bw_resc_start = bw_resc_end;
+
+	return 0;
+}
+
+/*
+ * membw_val:		execute benchmark and measure memory bandwidth on
+ *			the benchmark
+ * @benchmark_cmd:	benchmark command and its arguments
+ * @param:		parameters passed to membw_val()
+ *
+ * Return:		0 on success. non-zero on failure.
+ */
+int membw_val(char **benchmark_cmd, struct resctrl_val_param *param)
+{
+	char *resctrl_val = param->resctrl_val;
+	unsigned long bw_resc_start = 0;
+	struct sigaction sigact;
+	union sigval value;
+	int sig = 0, ret = 0;
+	FILE *fp;
+
+	if (strcmp(param->filename, "") == 0)
+		sprintf(param->filename, "stdio");
+
+	if (strcmp(param->bw_report, "") == 0)
+		param->bw_report = "total";
+
+	ret = validate_resctrl_feature_request(resctrl_val);
+	if (ret)
+		return ret;
+
+	if ((strcmp(resctrl_val, "mba")) == 0 ||
+	    (strcmp(resctrl_val, "mbm")) == 0) {
+		ret = validate_bw_report_request(param->bw_report);
+		if (ret)
+			return ret;
+	}
+
+	ret = remount_resctrlfs(param->mum_resctrlfs);
+	if (ret)
+		return ret;
+
+	/*
+	 * If benchmark wasn't successfully started by child, then child should
+	 * kill parent, so save parent's pid
+	 */
+	ppid = getpid();
+
+	/* File based synchronization between parent and child */
+	fp = fopen("sig", "w");
+	if (!fp || (fprintf(fp, "%d\n", 0) <= 0) || (fclose(fp) == EOF)) {
+		perror("Unable to establish sync bw parent & child");
+
+		return errno;
+	}
+
+	/*
+	 * Fork to start benchmark, save child's pid so that it can be killed
+	 * when needed
+	 */
+	bm_pid = fork();
+	if (bm_pid == -1) {
+		perror("Unable to fork");
+
+		return errno;
+	}
+
+	if (bm_pid == 0) {
+		/*
+		 * Mask all signals except SIGUSR1, parent uses SIGUSR1 to
+		 * start benchmark
+		 */
+		sigfillset(&sigact.sa_mask);
+		sigdelset(&sigact.sa_mask, SIGUSR1);
+
+		sigact.sa_sigaction = run_benchmark;
+		sigact.sa_flags = SA_SIGINFO;
+
+		/* Register for "SIGUSR1" signal from parent */
+		if (sigaction(SIGUSR1, &sigact, NULL))
+			PARENT_EXIT("Can't register child for signal");
+
+		/* Signal parent that child is ready */
+		fp = fopen("sig", "w");
+		if (!fp || (fprintf(fp, "%d\n", 1) <= 0) ||
+		    (fclose(fp) == EOF))
+			PARENT_EXIT("can't signal that child is ready");
+
+		/* Suspend child until delivery of "SIGUSR1" from parent */
+		sigsuspend(&sigact.sa_mask);
+	}
+
+	printf("Benchmark PID: %d\n", bm_pid);
+
+	/*
+	 * Register CTRL-C handler for parent, as it has to kill benchmark
+	 * before exiting
+	 */
+	sigact.sa_sigaction = ctrlc_handler;
+	sigemptyset(&sigact.sa_mask);
+	sigact.sa_flags = SA_SIGINFO;
+	if (sigaction(SIGINT, &sigact, NULL) ||
+	    sigaction(SIGHUP, &sigact, NULL)) {
+		perror("Can't register parent for CTRL-C handler");
+		ret = errno;
+		goto out;
+	}
+
+	value.sival_ptr = benchmark_cmd;
+
+	/* Taskset benchmark to specified cpu */
+	ret = taskset_benchmark(bm_pid, param->cpu_no);
+	if (ret)
+		goto out;
+
+	/* 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)
+		goto out;
+
+	if ((strcmp(resctrl_val, "mbm") == 0) ||
+	    (strcmp(resctrl_val, "mba") == 0)) {
+		ret = initialize_mem_bw_imc();
+		if (ret)
+			goto out;
+
+		initialize_mem_bw_resctrl(param->ctrlgrp, param->mongrp,
+					  param->cpu_no, resctrl_val);
+	}
+
+	/*
+	 * Parent should signal child to start executing benchmark only upon
+	 * receiving a signal from child saying that it's ready
+	 */
+	while (sig == 0) {
+		fp = fopen("sig", "r");
+		if (!fp) {
+			perror("Unable to open 'sig' file");
+			ret = errno;
+			goto out;
+		}
+		fscanf(fp, "%d\n", &sig);
+		if (fclose(fp) == EOF) {
+			perror("Unable to close 'sig' file");
+			ret = errno;
+			goto out;
+		}
+	}
+	if (system(RM_SIG_FILE) != 0)
+		perror("Unable to remove 'sig' file");
+
+	/* Signal child to start benchmark */
+	if (sigqueue(bm_pid, SIGUSR1, value) == -1) {
+		perror("Unable to signal child to start execution");
+		ret = errno;
+		goto out;
+	}
+
+	/* Give benchmark enough time to fully run */
+	sleep(1);
+
+	/* Test runs until the callback setup() tells the test to stop. */
+	while (1) {
+		if (strcmp(resctrl_val, "mbm") == 0) {
+			ret = param->setup(1, param);
+			if (ret) {
+				ret = 0;
+				break;
+			}
+
+			ret = measure_vals(param, &bw_resc_start);
+			if (ret)
+				break;
+		} else if ((strcmp(resctrl_val, "mba") == 0)) {
+			ret = param->setup(1, param->cpu_no);
+			if (ret) {
+				ret = 0;
+				break;
+			}
+
+			ret = measure_vals(param, &bw_resc_start);
+			if (ret)
+				break;
+		} else {
+			break;
+		}
+	}
+
+out:
+	kill(bm_pid, SIGKILL);
+	umount_resctrlfs();
+
+	return ret;
+}
diff --git a/tools/testing/selftests/resctrl/resctrl.h b/tools/testing/selftests/resctrl/resctrl.h
index fe3c3434df97..f1de2dee8f50 100644
--- a/tools/testing/selftests/resctrl/resctrl.h
+++ b/tools/testing/selftests/resctrl/resctrl.h
@@ -3,6 +3,7 @@
 #ifndef RESCTRL_H
 #define RESCTRL_H
 #include <stdio.h>
+#include <stdarg.h>
 #include <errno.h>
 #include <sched.h>
 #include <stdlib.h>
@@ -33,10 +34,35 @@
 		exit(EXIT_FAILURE);		\
 	} while (0)
 
+/*
+ * resctrl_val_param:	resctrl test parameters
+ * @resctrl_val:	Resctrl feature (Eg: mbm, mba.. etc)
+ * @ctrlgrp:		Name of the control monitor group (con_mon grp)
+ * @mongrp:		Name of the monitor group (mon grp)
+ * @cpu_no:		CPU number to which the benchmark would be binded
+ * @mum_resctrlfs:	Should the resctrl FS be remounted?
+ * @filename:		Name of file to which the o/p should be written
+ * @bw_report:		Bandwidth report type (reads vs writes)
+ * @setup:		Call back function to setup test environment
+ */
+struct resctrl_val_param {
+	char	*resctrl_val;
+	char	ctrlgrp[64];
+	char	mongrp[64];
+	int	cpu_no;
+	int	span;
+	int	mum_resctrlfs;
+	char	filename[64];
+	char	*bw_report;
+	char	*bm_type;
+	int	(*setup)(int num, ...);
+};
+
 pid_t bm_pid, ppid;
 int ben_count;
 
 int remount_resctrlfs(bool mum_resctrlfs);
+int umount_resctrlfs(void);
 char get_sock_num(int cpu_no);
 int validate_bw_report_request(char *bw_report);
 int validate_resctrl_feature_request(char *resctrl_val);
@@ -49,5 +75,6 @@ int write_bm_pid_to_resctrl(pid_t bm_pid, char *ctrlgrp, char *mongrp,
 int perf_event_open(struct perf_event_attr *hw_event, pid_t pid, int cpu,
 		    int group_fd, unsigned long flags);
 int run_fill_buf(int span, int malloc_and_init_memory, int memflush, int op);
+int membw_val(char **benchmark_cmd, struct resctrl_val_param *param);
 
 #endif /* RESCTRL_H */
-- 
2.5.0