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SubjectRe: [PATCH v7 04/13] selftests/resctrl: Add callback to start a benchmark
On Sat,  9 Feb 2019 18:50:33 -0800
Fenghua Yu <fenghua.yu@intel.com> wrote:

Hi,

> From: Sai Praneeth Prakhya <sai.praneeth.prakhya@intel.com>
>
> 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@intel.com>
> Signed-off-by: Arshiya Hayatkhan Pathan <arshiya.hayatkhan.pathan@intel.com>
> Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
> Signed-off-by: Babu Moger <babu.moger@amd.com>
> ---
> tools/testing/selftests/resctrl/resctrl.h | 27 ++
> tools/testing/selftests/resctrl/resctrl_val.c | 582 ++++++++++++++++++++++++++
> 2 files changed, 609 insertions(+)
>
> diff --git a/tools/testing/selftests/resctrl/resctrl.h b/tools/testing/selftests/resctrl/resctrl.h
> index 2e112934d48a..c286790ba24d 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>
> @@ -28,10 +29,35 @@
> 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
> + * @span: Memory bytes accessed in each benchmark iteration
> + * @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;
> + int (*setup)(int num, ...);
> +};
> +
> pid_t bm_pid, ppid;
>
> int remount_resctrlfs(bool mum_resctrlfs);
> int get_resource_id(int cpu_no, int *resource_id);
> +int umount_resctrlfs(void);
> int validate_bw_report_request(char *bw_report);
> int validate_resctrl_feature_request(char *resctrl_val);
> int taskset_benchmark(pid_t bm_pid, int cpu_no);
> @@ -44,5 +70,6 @@ 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(unsigned long span, int malloc_and_init_memory, int memflush,
> int op, char *resctrl_va);
> +int resctrl_val(char **benchmark_cmd, struct resctrl_val_param *param);
>
> #endif /* RESCTRL_H */
> diff --git a/tools/testing/selftests/resctrl/resctrl_val.c b/tools/testing/selftests/resctrl/resctrl_val.c
> index 2bb317715a2a..43c15e382892 100644
> --- a/tools/testing/selftests/resctrl/resctrl_val.c
> +++ b/tools/testing/selftests/resctrl/resctrl_val.c
> @@ -11,6 +11,7 @@
> */
> #include "resctrl.h"
>
> +#define MB (1024 * 1024)
> #define UNCORE_IMC "uncore_imc"
> #define READ_FILE_NAME "events/cas_count_read"
> #define WRITE_FILE_NAME "events/cas_count_write"
> @@ -48,6 +49,8 @@ struct imc_counter_config {
> int fd;
> };
>
> +static char mbm_total_path[1024];
> +static int imcs;
> static struct imc_counter_config imc_counters_config[MAX_IMCS][2];
>
> void membw_initialize_perf_event_attr(int i, int j)
> @@ -116,3 +119,582 @@ void get_event_and_umask(char *cas_count_cfg, int count, bool op)
> }
> }
> }
> +
> +static int open_perf_event(int i, int cpu_no, int j)
> +{
> + imc_counters_config[i][j].fd =
> + perf_event_open(&imc_counters_config[i][j].pe, -1, cpu_no, -1,
> + PERF_FLAG_FD_CLOEXEC);
> +
> + if (imc_counters_config[i][j].fd == -1) {
> + fprintf(stderr, "Error opening leader %llx\n",
> + imc_counters_config[i][j].pe.config);
> +
> + return -1;
> + }
> +
> + return 0;
> +}
> +
> +/* Get type and config (read and write) of an iMC counter */
> +static int read_from_imc_dir(char *imc_dir, int count)
> +{
> + char cas_count_cfg[1024], imc_counter_cfg[1024], imc_counter_type[1024];
> + FILE *fp;
> +
> + /* Get type of iMC counter */
> + sprintf(imc_counter_type, "%s%s", imc_dir, "type");
> + fp = fopen(imc_counter_type, "r");
> + if (!fp) {
> + perror("Failed to open imc counter type file");
> +
> + return -1;
> + }
> + if (fscanf(fp, "%u", &imc_counters_config[count][READ].type) <= 0) {
> + perror("Could not get imc type");
> + fclose(fp);
> +
> + return -1;
> + }
> + fclose(fp);
> +
> + imc_counters_config[count][WRITE].type =
> + imc_counters_config[count][READ].type;
> +
> + /* Get read config */
> + sprintf(imc_counter_cfg, "%s%s", imc_dir, READ_FILE_NAME);
> + fp = fopen(imc_counter_cfg, "r");
> + if (!fp) {
> + perror("Failed to open imc config file");
> +
> + return -1;
> + }
> + if (fscanf(fp, "%s", cas_count_cfg) <= 0) {
> + perror("Could not get imc cas count read");
> + fclose(fp);
> +
> + return -1;
> + }
> + fclose(fp);
> +
> + get_event_and_umask(cas_count_cfg, count, READ);
> +
> + /* Get write config */
> + sprintf(imc_counter_cfg, "%s%s", imc_dir, WRITE_FILE_NAME);
> + fp = fopen(imc_counter_cfg, "r");
> + if (!fp) {
> + perror("Failed to open imc config file");
> +
> + return -1;
> + }
> + if (fscanf(fp, "%s", cas_count_cfg) <= 0) {
> + perror("Could not get imc cas count write");
> + fclose(fp);
> +
> + return -1;
> + }
> + fclose(fp);
> +
> + get_event_and_umask(cas_count_cfg, count, WRITE);
> +
> + return 0;
> +}
> +
> +/*
> + * A system can have 'n' number of iMC (Integrated Memory Controller)
> + * counters, get that 'n'. For each iMC counter get it's type and config.
> + * Also, each counter has two configs, one for read and the other for write.
> + * A config again has two parts, event and umask.
> + * Enumerate all these details into an array of structures.
> + *
> + * Return: >= 0 on success. < 0 on failure.
> + */
> +static int num_of_imcs(void)
> +{
> + unsigned int count = 0;
> + char imc_dir[1024];
> + struct dirent *ep;
> + int ret;
> + DIR *dp;
> +
> + dp = opendir(DYN_PMU_PATH);
> + if (dp) {

Changing this to: if (!dp) {
and handling the error case first makes this more readable and avoids the indentation.

> + while ((ep = readdir(dp))) {
> + if (strstr(ep->d_name, UNCORE_IMC)) {
> + sprintf(imc_dir, "%s/%s/", DYN_PMU_PATH,
> + ep->d_name);
> + ret = read_from_imc_dir(imc_dir, count);
> + if (ret) {
> + closedir(dp);
> +
> + return ret;
> + }
> + count++;
> + }
> + }
> + closedir(dp);
> + if (count == 0) {
> + perror("Unable find iMC counters!\n");
> +
> + return -1;
> + }
> + } else {
> + perror("Unable to open PMU directory!\n");
> +
> + return -1;
> + }
> +
> + return count;
> +}
> +
> +static int initialize_mem_bw_imc(void)
> +{
> + int imc, j;
> +
> + imcs = num_of_imcs();
> + if (imcs <= 0)
> + return imcs;
> +
> + /* Initialize perf_event_attr structures for all iMC's */
> + for (imc = 0; imc < imcs; imc++) {
> + for (j = 0; j < 2; j++)
> + membw_initialize_perf_event_attr(imc, j);
> + }
> +
> + return 0;
> +}
> +
> +/*
> + * get_mem_bw_imc: Memory band width as reported by iMC counters
> + * @cpu_no: CPU number that the benchmark PID is binded to
> + * @bw_report: Bandwidth report type (reads, writes)
> + *
> + * Memory B/W utilized by a process on a socket can be calculated using
> + * iMC counters. Perf events are used to read these counters.
> + *
> + * Return: >= 0 on success. < 0 on failure.
> + */
> +static float get_mem_bw_imc(int cpu_no, char *bw_report)
> +{
> + float reads, writes, of_mul_read, of_mul_write;
> + int imc, j, ret;
> +
> + /* Start all iMC counters to log values (both read and write) */
> + reads = 0, writes = 0, of_mul_read = 1, of_mul_write = 1;
> + for (imc = 0; imc < imcs; imc++) {
> + for (j = 0; j < 2; j++) {
> + ret = open_perf_event(imc, cpu_no, j);
> + if (ret)
> + return -1;
> + }
> + for (j = 0; j < 2; j++)
> + membw_ioctl_perf_event_ioc_reset_enable(imc, j);
> + }
> +
> + sleep(1);
> +
> + /* Stop counters after a second to get results (both read and write) */
> + for (imc = 0; imc < imcs; imc++) {
> + for (j = 0; j < 2; j++)
> + membw_ioctl_perf_event_ioc_disable(imc, j);
> + }
> +
> + /*
> + * Get results which are stored in struct type imc_counter_config
> + * Take over flow into consideration before calculating total b/w
> + */
> + for (imc = 0; imc < imcs; imc++) {
> + struct imc_counter_config *r =
> + &imc_counters_config[imc][READ];
> + struct imc_counter_config *w =
> + &imc_counters_config[imc][WRITE];
> +
> + if (read(r->fd, &r->return_value,
> + sizeof(struct membw_read_format)) == -1) {
> + perror("Couldn't get read b/w through iMC");
> +
> + return -1;
> + }
> +
> + if (read(w->fd, &w->return_value,
> + sizeof(struct membw_read_format)) == -1) {
> + perror("Couldn't get write bw through iMC");
> +
> + return -1;
> + }
> +
> + __u64 r_time_enabled = r->return_value.time_enabled;
> + __u64 r_time_running = r->return_value.time_running;
> +
> + if (r_time_enabled != r_time_running)
> + of_mul_read = (float)r_time_enabled /
> + (float)r_time_running;
> +
> + __u64 w_time_enabled = w->return_value.time_enabled;
> + __u64 w_time_running = w->return_value.time_running;
> +
> + if (w_time_enabled != w_time_running)
> + of_mul_write = (float)w_time_enabled /
> + (float)w_time_running;
> + reads += r->return_value.value * of_mul_read * SCALE;
> + writes += w->return_value.value * of_mul_write * SCALE;
> + }
> +
> + for (imc = 0; imc < imcs; imc++) {
> + close(imc_counters_config[imc][READ].fd);
> + close(imc_counters_config[imc][WRITE].fd);
> + }
> +
> + if (strcmp(bw_report, "reads") == 0)
> + return reads;
> +
> + if (strcmp(bw_report, "writes") == 0)
> + return writes;
> +
> + return (reads + writes);
> +}
> +
> +void set_mbm_path(const char *ctrlgrp, const char *mongrp, int resource_id)
> +{
> + if (ctrlgrp && mongrp)
> + sprintf(mbm_total_path, CON_MON_MBM_LOCAL_BYTES_PATH,
> + RESCTRL_PATH, ctrlgrp, mongrp, resource_id);
> + else if (!ctrlgrp && mongrp)
> + sprintf(mbm_total_path, MON_MBM_LOCAL_BYTES_PATH, RESCTRL_PATH,
> + mongrp, resource_id);
> + else if (ctrlgrp && !mongrp)
> + sprintf(mbm_total_path, CON_MBM_LOCAL_BYTES_PATH, RESCTRL_PATH,
> + ctrlgrp, resource_id);
> + else if (!ctrlgrp && !mongrp)
> + sprintf(mbm_total_path, MBM_LOCAL_BYTES_PATH, RESCTRL_PATH,
> + resource_id);
> +}
> +
> +/*
> + * initialize_mem_bw_resctrl: Appropriately populate "mbm_total_path"
> + * @ctrlgrp: Name of the control monitor group (con_mon grp)
> + * @mongrp: Name of the monitor group (mon grp)
> + * @cpu_no: CPU number that the benchmark PID is binded to
> + * @resctrl_val: Resctrl feature (Eg: mbm, mba.. etc)
> + */
> +static void initialize_mem_bw_resctrl(const char *ctrlgrp, const char *mongrp,
> + int cpu_no, char *resctrl_val)
> +{
> + int resource_id;
> +
> + if (get_resource_id(cpu_no, &resource_id) < 0) {
> + perror("Could not get resource_id");
> + return;
> + }
> +
> + if (strcmp(resctrl_val, "mbm") == 0)
> + set_mbm_path(ctrlgrp, mongrp, resource_id);
> +
> + if ((strcmp(resctrl_val, "mba") == 0)) {
> + if (ctrlgrp)
> + sprintf(mbm_total_path, CON_MBM_LOCAL_BYTES_PATH,
> + RESCTRL_PATH, ctrlgrp, resource_id);
> + else
> + sprintf(mbm_total_path, MBM_LOCAL_BYTES_PATH,
> + RESCTRL_PATH, resource_id);
> + }
> +}
> +
> +/*
> + * Get MBM Local bytes as reported by resctrl FS
> + * For MBM,
> + * 1. If con_mon grp and mon grp are given, then read from con_mon grp's mon grp
> + * 2. If only con_mon grp is given, then read from con_mon grp
> + * 3. If both are not given, then read from root con_mon grp
> + * For MBA,
> + * 1. If con_mon grp is given, then read from it
> + * 2. If con_mon grp is not given, then read from root con_mon grp
> + */
> +static unsigned long get_mem_bw_resctrl(void)
> +{
> + unsigned long mbm_total = 0;
> + FILE *fp;
> +
> + fp = fopen(mbm_total_path, "r");
> + if (!fp) {
> + perror("Failed to open total bw file");
> +
> + return -1;
> + }
> + if (fscanf(fp, "%lu", &mbm_total) <= 0) {
> + perror("Could not get mbm local bytes");
> + fclose(fp);
> +
> + return -1;
> + }
> + fclose(fp);
> +
> + 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)
> +{
> + unsigned long diff = labs(bw_imc - bw_resc);

Since bw_imc is float (why, actually?) this should be fabs(). clang
complains about it.

> + 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: %lu\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 Mem_BW_resc: %lu \t Difference: %lu\n",
> + bm_pid, bw_imc, 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;
> +}
> +
> +/*
> + * resctrl_val: execute benchmark and measure memory bandwidth on
> + * the benchmark
> + * @benchmark_cmd: benchmark command and its arguments
> + * @param: parameters passed to resctrl_val()
> + *
> + * Return: 0 on success. non-zero on failure.
> + */
> +int resctrl_val(char **benchmark_cmd, struct resctrl_val_param *param)
> +{
> + int ret = 0, pipefd[2], pipe_message = 0;

If I get this correctly, we just need to pipe for asynchronous signalling.
So can't we actually use a signal() call here? At least we should make
this pipe_message a single char. This avoids some nasty problems with
read() and write() possibly returning early.

> + char *resctrl_val = param->resctrl_val;
> + unsigned long bw_resc_start = 0;
> + struct sigaction sigact;
> + union sigval value;
> + FILE *fp;
> +
> + if (strcmp(param->filename, "") == 0)
> + sprintf(param->filename, "stdio");
> +
> + if (strcmp(param->bw_report, "") == 0)
> + param->bw_report = "total";
> +
> + 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) {
> + perror("Failed to open sig file");
> +
> + return -1;
> + }
> + if (fprintf(fp, "%d\n", 0) <= 0) {
> + perror("Unable to establish sync bw parent & child");
> + fclose(fp);
> +
> + return -1;
> + }
> + fclose(fp);
> +
> + if (pipe(pipefd)) {
> + perror("Unable to create pipe");
> +
> + return -1;
> + }
> +
> + /*
> + * 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 -1;
> + }
> +
> + 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");
> +
> + /* Tell parent that child is ready */
> + close(pipefd[0]);
> + pipe_message = 1;
> + write(pipefd[1], &pipe_message, sizeof(pipe_message));

gcc -O complains about an unchecked return value of write() here.
We could just compare against sizeof(pipe_message) and bail out if it's smaller.

> + close(pipefd[1]);
> +
> + /* Suspend child until delivery of "SIGUSR1" from parent */
> + sigsuspend(&sigact.sa_mask);
> +
> + PARENT_EXIT("Child is done");
> + }
> +
> + 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 control&monitoring 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 waits for child to be ready. */
> + close(pipefd[1]);
> + while (pipe_message != 1)
> + read(pipefd[0], &pipe_message, sizeof(pipe_message));

Same thing with checking the return value here.

Cheers,
Andre.

> + close(pipefd[0]);
> +
> + /* 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);
> + 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;
> +}

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