Re: [Lse-tech] Re: multi-queue scheduler update

[Davide Libenzi]

On Thursday 18 January 2001 17:39, Andrea Arcangeli wrote:
> On Thu, Jan 18, 2001 at 04:52:25PM -0800, Mike Kravetz wrote:
> > was less than the number of processors.  I'll give the tests a try
> > with a smaller number of threads.  I'm also open to suggestions for
>
> OK!
>
> > what benchmarks/test methods I could use for scheduler testing.  If
> > you remember what people have used in the past, please let me know.
>
> It was this one IIRC (it spawns threads calling sched_yield() in loop).
>
> /*
>   Tester for the kernel's speed in scheduling.
>   (C) 1999 / Willy Tarreau <[e-mail]>
>
>   Modified by Davide Libenzi <[e-mail]>
>
>
>   You can do whatever you want with this program, but I'm not
>   responsible for any misuse. Be aware that it can heavily load
>   a host. As it is multithreaded, it might take advantages of SMP.
>
>   It basically creates a growing amount of threads and measures
>   their cumulative work (i.e. loop iterations/second). The output
>   is easily useable by gnuplot.
>
>   To compile, you need libpthread :
>
>      gcc -O2 -fomit-frame-pointer -o threads threads.c -lpthread
>
>   Output on stdout is :
>      <nb_threads> <average_work> <zero_work_threads> <std_deviation>
>
> */
>
> #include <stdio.h>
> #include <pthread.h>
> #include <signal.h>
> #include <unistd.h>
> #include <time.h>
>
>
>
> #define MAXTHREADS	450
> #define MEASURE_TIME	60
>
>
>
> pthread_t       thr[MAXTHREADS];
> int             nbthreads = MAXTHREADS;
> int             measure_time = MEASURE_TIME;
> volatile        actthreads = 0;
>
> long long int   totalwork[MAXTHREADS];
> volatile int    stop = 0,
>                 start = 0,
>                 count = 0;
>
> void            oneatwork(int thr)
> {
>     int             i;
>     while (!start)              /* don't disturb pthread_create() */
>         usleep(10000);
>
>     actthreads++;
>     while (!stop)
>     {
>         if (count)
>             totalwork[thr]++;
>
>         syscall(158); /* sys_sched_yield() */
>     }
>     actthreads--;
>     pthread_exit(0);
> }
>
> main(int argc, char **argv)
> {
>
>     int             i,
>                     err,
>                     avgwork,
>                     thrzero;
>     long long int   value,
>                     avgvalue;
>     double          sqrdev;
>     time_t          ts,
>                     te;
>
>     if (argc < 3)
>     {
>         printf("usage: %s  threads  time\n", argv[0]);
>         exit(1);
>     }
>
>     nbthreads = atoi(argv[1]);
>     measure_time = atoi(argv[2]);
>
>
>     start = 0;
>     count = 0;
>     stop = 0;
>     actthreads = 0;
>     thrzero = 0;
>     value = 0;
>     sqrdev = 0.0;
>
>     fprintf(stderr, "\nCreating %d threads ...", nbthreads);
>     for (i = 0; i < nbthreads; i++)
>     {
>         if ((err = pthread_create(&thr[i], NULL, (void *) &oneatwork, (void
> *) i)) != 0) {
>             fprintf(stderr, "thread %d pthread_create=%d -> ", i, err);
>             perror("");
>             exit(1);
>         }
>         pthread_detach(thr[i]);
>     }
>
>     for (i = 0; i < nbthreads; i++)
>         totalwork[i] = 0;
>
>     fprintf(stderr, " OK !\nWaiting for all threads to start ...");
>
>     start = 1;
>     while (actthreads != nbthreads)
>         usleep(10000);         /* waiting for a bit of stability */
>
>     fprintf(stderr, "Go !\n");
>
>     count = 1;
>     time(&ts);
>
>     sleep(measure_time);
>
>     count = 0;
>     stop = 1;
>     time(&te);
>
>
>     for (i = 0; i < nbthreads; i++)
>     {
>         value += totalwork[i];
>         if (totalwork[i] == 0)
>             ++thrzero;
>     }
>     avgvalue = value / nbthreads;
>     value /= (int) difftime(te, ts);
>     avgwork = (int) (value / nbthreads);
>
>     for (i = 0; i < nbthreads; i++)
>     {
>         double          difvv = (double) (totalwork[i] - avgvalue);
>
>         sqrdev += difvv * difvv;
>     }
>
>     while (actthreads > 0)
>         usleep(10000);
>
>     printf("%d\t\t%lld\t\t%d\t\t%d\t\t%f\n", nbthreads, value, avgwork,
> thrzero, sqrdev / ((double) nbthreads * avgvalue * avgvalue));
>
>     exit(0);
>
> }
>

Andrea found it before me :)

- Davide