Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S967395AbaLKW5g (ORCPT ); Thu, 11 Dec 2014 17:57:36 -0500 Received: from smtp2.provo.novell.com ([137.65.250.81]:51479 "EHLO smtp2.provo.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S967047AbaLKW5c (ORCPT ); Thu, 11 Dec 2014 17:57:32 -0500 Message-ID: <1418338641.9432.5.camel@stgolabs.net> Subject: Re: [PATCH v3] Perf Bench: Locking Microbenchmark From: Davidlohr Bueso To: Tuan Bui Cc: linux-kernel@vger.kernel.org, a.p.zijlstra@chello.nl, paulus@samba.org, acme@kernel.org, artagnon@gmail.com, jolsa@redhat.com, dvhart@linux.intel.com, Aswin Chandramouleeswaran , Jason Low , akpm@linux-foundation.org, mingo@kernel.org Date: Thu, 11 Dec 2014 14:57:21 -0800 In-Reply-To: <1418165693.6540.5.camel@u64> References: <1418165693.6540.5.camel@u64> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.12.7 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 ' 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 > + */ > + > +#include "../perf.h" > +#include "../util/util.h" > +#include "../util/stat.h" > +#include "../util/parse-options.h" > +#include "../util/header.h" > +#include "bench.h" > + > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > +#include > + > +#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/ end_nr = ncpus * + 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 ", > + 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. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/