On Tue, 2014-12-09 at 14:54 -0800, Tuan Bui wrote:
> [root@u64 ~]# perf bench locking vfs
> # Running 'locking/vfs' benchmark:
>
> 100 processes: throughput = 342506 average opts/sec all processes
> 100 processes: throughput = 3425 average opts/sec per process
>
> 200 processes: throughput = 341309 average opts/sec all processes
> 200 processes: throughput = 1706 average opts/sec per process
> ...
What's the point in displaying the ops/sec/process? Could the not mean
be displayed at the end only? Or display it as you do but with a verbose
option?
One thing missing here that really should be addressed is multiple runs
and statistic reports. Take a look and make use of 'perf bench -r <N>'
and how we use it for, say, futexes:
./perf bench -r 5 futex requeue
# Running 'futex/requeue' benchmark:
Run summary [PID 19084]: Requeuing 4 threads (from [private] 0x74459c to
0x744598), 1 at a time.
[Run 1]: Requeued 4 of 4 threads in 0.0090 ms
[Run 2]: Requeued 4 of 4 threads in 0.0100 ms
[Run 3]: Requeued 4 of 4 threads in 0.0090 ms
[Run 4]: Requeued 4 of 4 threads in 0.0110 ms
[Run 5]: Requeued 4 of 4 threads in 0.0120 ms
Requeued 4 of 4 threads in 0.0102 ms (+-5.72%)
[...]
> diff --git a/tools/perf/bench/locking.c b/tools/perf/bench/locking.c
> new file mode 100644
> index 0000000..70222bb
> --- /dev/null
> +++ b/tools/perf/bench/locking.c
> @@ -0,0 +1,336 @@
> +/*
> + * locking.c
> + *
> + * Simple micro benchmark that stress kernel locking contention with
> + * creat(2) system call by spawning multiple processes to call
> + * this system call.
> + *
> + * Results output are average operations/sec for all processes and
> + * average operations/sec per process.
> + *
> + * Tuan Bui <tuan.d....@hp.com>
> + */
> +
> +#include "../perf.h"
> +#include "../util/util.h"
> +#include "../util/stat.h"
> +#include "../util/parse-options.h"
> +#include "../util/header.h"
> +#include "bench.h"
> +
> +#include <err.h>
> +#include <stdlib.h>
> +#include <sys/time.h>
> +#include <unistd.h>
> +#include <sys/resource.h>
> +#include <linux/futex.h>
> +#include <sys/mman.h>
> +#include <sys/syscall.h>
> +#include <sys/types.h>
> +#include <signal.h>
> +#include <dirent.h>
> +
> +#define NOTSET -1
You don't need this, just initialize bench_dur and num_jobs to 0, if
nothing is set, its a bogus value anyway.
> +struct worker {
> + pid_t pid;
> + unsigned int order_id;
> + char str[50];
> +};
> +
> +struct timeval start, end, total;
> +static unsigned int start_nr = 100;
> +static unsigned int end_nr = 1100;
> +static unsigned int increment_by = 100;
No, these default values need to be dynamic and scale by number of CPUs
to make sense on different systems. ie:
start_nr = 1;
inc = ncpus/<N>
end_nr = ncpus * <M> + inc
I'll let you see what N and M could be, but in general you want small
increments and a larger end_nr to stress the underlying lock as much as
possible (ie N=2, M=5).
> +static int bench_dur = NOTSET;
> +static int num_jobs = NOTSET;
> +static bool run_jobs;
> +static int n_pro;
As we add more benchmarks to 'bench locking' this can be unified into a
single context structure, or maybe something like 'struct params' like
we do in numa workloads.
> +/* Shared variables between fork processes*/
nit: please allow a space before closing the comment.
> +unsigned int *finished, *setup;
> +unsigned long long *shared_workers;
same suggestion as the context one above.
> +char *tmp_dir;
> +pid_t *p_id;
> +/* all processes will block on the same futex */
> +u_int32_t *futex;
Any reason why you're making it a pointer? you can just pass it to
futex(2) by reference.
> +
> +static const struct option options[] = {
> + OPT_UINTEGER('s', "start", &start_nr, "Number of processes to start"),
> + OPT_UINTEGER('e', "end", &end_nr, "Number of processes to end"),
> + OPT_UINTEGER('i', "increment", &increment_by, "Numbers of processes to
> increment)"),
> + OPT_INTEGER('r', "runtime", &bench_dur, "Specify benchmark runtime in
> seconds"),
> + OPT_INTEGER('j', "jobs", &num_jobs, "Specify number of jobs per
> process"),
> + OPT_END()
> +};
> +
> +static const char * const bench_locking_vfs_usage[] = {
> + "perf bench locking vfs <options>",
> + NULL
> +};
> +
> +/* Clean up if SIGINT is raised */
> +static void sigint_handler(int sig __maybe_unused,
> + siginfo_t *info __maybe_unused,
> + void *uc __maybe_unused)
> +{
> + DIR *dir;
> + struct dirent *file;
> + char fp[50];
> + int i;
> +
> + /* If child process exit*/
> + if (getpid() != *p_id)
> + exit(0);
> + /* if parent process wait for all child processes to exit and then
> clean up */
nit again: Please be consistent when commenting, either start with a cap
or don't.
> + else {
> + /* Wait for all child processes exit before cleaning up the dir
> */
> + for (i = 0; i < n_pro; i++)
> + wait(NULL);
> +
> + dir = opendir(tmp_dir);
> + if (dir == NULL)
> + err(EXIT_FAILURE, "opendir");
> + while ((file = readdir(dir))) {
> + sprintf(fp, "%s/%s", tmp_dir, file->d_name);
> + unlink(fp);
> + }
> + if ((rmdir(tmp_dir)) < 0)
> + err(EXIT_FAILURE, "rmdir");
> + exit(0);
> + }
> +}
> +
> +/* Running bench vfs workload */
> +static void *run_bench_vfs(struct worker *workers)
> +{
> + int fd;
> + unsigned long long nr_ops = 0;
> + int jobs = num_jobs;
> +
> + sprintf(workers->str, "%s/%d-XXXXXX", tmp_dir, getpid());
> + if ((mkstemp(workers->str)) < 0)
> + err(EXIT_FAILURE, "mkstemp");
> +
> + /* Signal to parent process and wait till all processes/ are ready run
> */
> + setup[workers->order_id] = 1;
> + syscall(SYS_futex, futex, FUTEX_WAIT, 0, NULL, NULL, 0);
> +
> + /* Start of the benchmark keep looping till parent process signal
> completion */
> + while ((run_jobs ? (jobs > 0) : (!*finished))) {
> + fd = creat(workers->str, S_IRWXU);
> + if (fd < 0)
> + err(EXIT_FAILURE, "creat");
> + nr_ops++;
> + if (run_jobs)
> + jobs--;
> + close(fd);
> + }
> +
> + if ((unlink(workers->str)) < 0)
> + err(EXIT_FAILURE, "unlink");
> + shared_workers[workers->order_id] = nr_ops;
> + setup[workers->order_id] = 0;
> + exit(0);
> +}
> +
> +/* Setting shared variable finished and shared_workers */
It would be nice to further expand this comment. Why did you choose to
create so many shared mappings?
> +static void setup_shared(void)
> +{
> + unsigned int *finished_tmp, *setup_tmp;
> + unsigned long long *shared_workers_tmp;
> + u_int32_t *futex_tmp;
> +
> +
> + /* finished shared var is use to signal start and end of benchmark */
> + finished_tmp = (void *)mmap(0, sizeof(unsigned int),
> PROT_READ|PROT_WRITE,
> + MAP_SHARED|MAP_ANONYMOUS, -1, 0);
> + if (finished_tmp == (void *) -1)
> + err(EXIT_FAILURE, "mmap finished");
> + finished = finished_tmp;
> +
> + /* shared_workers is an array of ops perform by each process */
> + shared_workers_tmp = (void *)mmap(0, sizeof(unsigned long long)*end_nr,
> + PROT_READ|PROT_WRITE, MAP_SHARED|MAP_ANONYMOUS, -1, 0);
> + if (shared_workers_tmp == (void *) -1)
> + err(EXIT_FAILURE, "mmap shared_workers");
> + shared_workers = shared_workers_tmp;
> +
> + /* setup is use for each processes to signal that it is done
> + * setting up for the benchmark and is ready to run */
nit: multi line comments should be in the form:
/*
* lala
*/
For this kind of style crap, you'll want to run checkpatch ;)
> + setup_tmp = (void *)mmap(0, sizeof(unsigned int)*end_nr,
> + PROT_READ|PROT_WRITE, MAP_SHARED|MAP_ANONYMOUS, -1, 0);
> + if (setup_tmp == (void *) -1)
> + err(EXIT_FAILURE, "mmap setup");
> + setup = setup_tmp;
> +
> + /* Processes will sleep on this futex until all other processes
> + * are done setting up and are ready to run */
> + futex_tmp = (void *)mmap(0, sizeof(u_int32_t), PROT_READ|PROT_WRITE,
> + MAP_SHARED|MAP_ANONYMOUS, -1, 0);
> + if (futex_tmp == (void *) -1)
> + err(EXIT_FAILURE, "mmap futex");
> + futex = futex_tmp;
> + (*futex) = 0;
I'm not following, why you need this? I could be missing something, but
it seems you're over complicating things...
> + /* Setting a tmp dir for all processes to write to */
> + tmp_dir = (void *)mmap(0, sizeof(char) * 255, PROT_READ|PROT_WRITE,
> + MAP_SHARED|MAP_ANONYMOUS, -1, 0);
> + if (tmp_dir == (void *) -1)
> + err(EXIT_FAILURE, "mmap finished");
> +
> + /* Setting up parent id to handle sigint */
> + p_id = (void *)mmap(0, sizeof(pid_t), PROT_READ|PROT_WRITE,
> + MAP_SHARED|MAP_ANONYMOUS, -1, 0);
> + if (p_id == (void *) -1)
> + err(EXIT_FAILURE, "mmap p_id");
> + *p_id = getpid();
> +
> + /* Creating tmp dir for all process to write to */
> + sprintf(tmp_dir, "%d-XXXXXX", *p_id);
> + if ((mkdtemp(tmp_dir)) == NULL)
> + err(EXIT_FAILURE, "mkdtemp");
> +}
> +
> +/* Freeing shared variables */
> +static void free_resources(void)
> +{
> + if ((rmdir(tmp_dir)) == -1)
> + err(EXIT_FAILURE, "rmdir");
> +
> + if ((munmap(finished, sizeof(unsigned int)) == -1))
> + err(EXIT_FAILURE, "munmap finished");
> +
> + if ((munmap(shared_workers, sizeof(unsigned long long) * end_nr) == -1))
> + err(EXIT_FAILURE, "munmap shared_workers");
> +
> + if ((munmap(setup, sizeof(unsigned int) * end_nr) == -1))
> + err(EXIT_FAILURE, "munmap setup");
> +
> + if ((munmap(futex, sizeof(u_int32_t))) == -1)
> + err(EXIT_FAILURE, "munmap futex");
> +
> + if ((munmap(tmp_dir, sizeof(char) * 50) == -1))
> + err(EXIT_FAILURE, "munmap tmp_dir");
> +
> + if ((munmap(p_id, sizeof(pid_t)) == -1))
> + err(EXIT_FAILURE, "munmap p_id");
> +}
> +
> +/* Start to spawn workers and wait till all workers have been
> + * created before starting workload */
> +static void spawn_workers(void *(*bench_ptr) (struct worker *))
> +{
> + pid_t child;
> + unsigned int i, j, k;
Please use meaningful variable names, there are used more than just a
simple loop counter.
> + struct worker workers;
> + unsigned long long total_ops;
> + unsigned int total_workers;
> +
> + setup_shared();
> +
> + /* This loop through all the run each is increment by increment_by */
> + for (i = start_nr; i <= end_nr; i += increment_by) {
> +
> + for (j = 0; j < i; j++) {
> + if (!fork())
> + break;
> + }
> +
> + child = getpid();
> + /* Initialize child worker struct and run benchmark */
> + if (child != *p_id) {
> + workers.order_id = j;
> + workers.pid = child;
> + bench_ptr(&workers);
> + }
> + /* Parent to sleep during the duration of benchmark */
> + else{
> + n_pro = i;
> + /* Make sure all child process are created and setup
> + * before starting benchmark for bench_dur durations */
> + do {
> + total_workers = 0;
> + for (k = 0; k < i; k++)
> + total_workers = total_workers +
> setup[k];
> + } while (total_workers != i);
> +
> + /* Wake up all sleeping process to run the benchmark */
> + (*futex) = 1;
> + syscall(SYS_futex, futex, FUTEX_WAKE, i, NULL, NULL, 0);
Please no, we have futex.h wrappers for that. You also need to confirm
that the wakeups did in fact occur (check the return value of
futex_wake()).
> +
> + /* If run time parameters is set */
> + if (!run_jobs) {
> + /* All proccesses are ready signal them to run
> */
> + gettimeofday(&start, NULL);
> + sleep(bench_dur);
> + (*finished) = 1;
> + gettimeofday(&end, NULL);
> + timersub(&end, &start, &total);
> +
> + for (k = 0; k < i; k++)
> + wait(NULL);
> + }
> + /* If jobs per proccesses is set */
> + else {
> + /* All proccesses are ready signal them to run
> */
> + gettimeofday(&start, NULL);
> + /* Wait for all process to terminate before
> getting outputs */
> + for (k = 0; k < i; k++)
> + wait(NULL);
> + gettimeofday(&end, NULL);
> + timersub(&end, &start, &total);
> + }
> +
> + /* Sum up all the ops by each process and report */
> + total_ops = 0;
> + for (k = 0; k < i; k++)
> + total_ops = total_ops + shared_workers[k];
> +
> + printf("\n%6d processes: throughput = %llu average
> opts/sec all processes\n",
> + i, (total_ops / (!total.tv_sec ? 1 :
> total.tv_sec)));
> +
> + printf("%6d processes: throughput = %llu average
> opts/sec per process\n",
> + i, ((total_ops/(!total.tv_sec ? 1 :
> total.tv_sec))/(!i ? 1 : i)));
At this point, its pretty hard to make sense of what on earth this
output represents. Can you break it up a bit?
> +
> + /* Reset back to 0 for next run */
> + (*finished) = 0;
> + (*futex) = 0;
Reporting should be a different function.
> + }
> + }
> + free_resources();
> +}
> +
> +int bench_locking_vfs(int argc, const char **argv,
> + const char *prefix __maybe_unused)
> +{
> + struct sigaction sa;
> +
> + sigfillset(&sa.sa_mask);
> + sa.sa_sigaction = sigint_handler;
> + sa.sa_flags = SA_SIGINFO;
> + sigaction(SIGINT, &sa, NULL);
You probably want to setup signal callbacks once you verify the user
input is correct and ready to fork ;)
> +
> + argc = parse_options(argc, argv, options, bench_locking_vfs_usage, 0);
> +
> + /* If errors parsing options */
> + if (argc || ((bench_dur != NOTSET) && (num_jobs != NOTSET))) {
This should only be if (argc), evaluating bench_dur and num_jobs should
come later.
> + usage_with_options(bench_locking_vfs_usage, options);
> + exit(EXIT_FAILURE);
> + }
> + /* If both run time and job per process is set */
> + if (argc || ((bench_dur != NOTSET) && (num_jobs != NOTSET))) {
This condition is the same as the above. Just get rid of the argc check
here.
> + fprintf(stderr, "\n runtime and jobs options can not both be
> specified\n");
> + usage_with_options(bench_locking_vfs_usage, options);
> + exit(EXIT_FAILURE);
> + }
> +
> + /* If both run time and jobs options is not set default to run time
> only*/
> + if ((bench_dur == NOTSET) && (num_jobs == NOTSET))
> + bench_dur = 5;
> +
> + if (num_jobs != NOTSET)
> + run_jobs = true;
> +
> + spawn_workers(run_bench_vfs);
> + return 0;
> +}
Overall this is shaping up nicely I think, thanks for doing this.
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