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benchmarks/latmus: drop background load generation 

Let the user generate any background noise as/if required. We simply
cannot approximate the typical load of the target system in a reliable
manner with a fixed dd-like loop.
This commit is contained in:
Philippe Gerum 2020-01-04 18:29:49 +01:00
parent a7f538be1a
commit ff99204ba2
1 changed files with 2 additions and 81 deletions
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83
benchmarks/latmus.c
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@ -49,7 +49,7 @@ static cpu_set_t isolated_cpus;
static int test_irqlat, test_klat,
test_ulat, test_gpiolat;
static int reset, load = -1, background,
static int reset, background,
verbosity = 1, abort_on_switch,
abort_threshold;
@ -88,7 +88,7 @@ static sem_t logger_done;
static bool c_state_restricted;
#define short_optlist "ikurLNqbamtp:A:T:v:l:g:H:P:c:Z:z:I:O:"
#define short_optlist "ikurqbamtp:A:T:v:l:g:H:P:c:Z:z:I:O:"
static const struct option options[] = {
{
@ -111,16 +111,6 @@ static const struct option options[] = {
.has_arg = no_argument,
.val = 'r'
},
{
.name = "load",
.has_arg = no_argument,
.val = 'L'
},
{
.name = "noload",
.has_arg = no_argument,
.val = 'N'
},
{
.name = "quiet",
.has_arg = no_argument,
@ -233,57 +223,6 @@ static void create_responder(pthread_t *tid, void *(*responder)(void *))
error(1, ret, "sampling thread");
}
static void *load_thread(void *arg)
{
ssize_t nbytes, ret;
struct timespec rqt;
int fdi, fdo;
char buf[512];
fdi = open("/dev/zero", O_RDONLY);
if (fdi < 0)
error(1, errno, "/dev/zero");
fdo = open("/dev/null", O_WRONLY);
if (fdi < 0)
error(1, errno, "/dev/null");
rqt.tv_sec = 0;
rqt.tv_nsec = 2000000;
for (;;) {
clock_nanosleep(CLOCK_MONOTONIC, 0, &rqt, NULL);
nbytes = read(fdi, buf, sizeof(buf));
if (nbytes <= 0)
error(1, EIO, "load streaming");
if (nbytes > 0) {
ret = write(fdo, buf, nbytes);
(void)ret;
}
}
return NULL;
}
static void create_load(pthread_t *tid)
{
struct sched_param param;
pthread_attr_t attr;
int ret;
pthread_attr_init(&attr);
pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
pthread_attr_setinheritsched(&attr, PTHREAD_EXPLICIT_SCHED);
pthread_attr_setschedpolicy(&attr, SCHED_FIFO);
param.sched_priority = 1;
pthread_attr_setschedparam(&attr, &param);
pthread_attr_setstacksize(&attr, EVL_STACK_DEFAULT);
ret = pthread_create(tid, &attr, load_thread, NULL);
pthread_attr_destroy(&attr);
if (ret)
error(1, ret, "load thread");
}
#define ONE_BILLION 1000000000
#define TEN_MILLIONS 10000000
@ -1169,8 +1108,6 @@ static void usage(void)
fprintf(stderr, "-P --priority=<prio> responder thread priority [=90]\n");
fprintf(stderr, "-c --cpu=<n> pin responder thread to CPU [=0]\n");
fprintf(stderr, "-r --reset reset core timer gravity to factory default\n");
fprintf(stderr, "-L --load enable load generation [on if tuning]\n");
fprintf(stderr, "-n --noload disable load generation\n");
fprintf(stderr, "-b --background run in the background (daemon mode)\n");
fprintf(stderr, "-a --mode-abort abort upon unexpected switch to in-band mode\n");
fprintf(stderr, "-A --max-abort=<us> abort if maximum latency exceeds threshold\n");
@ -1193,7 +1130,6 @@ int main(int argc, char *const argv[])
int ret, c, spec, type, max_prio;
const char *plot_filename = NULL;
struct sigaction sa;
pthread_t loadgen;
char *endptr;
opterr = 0;
@ -1218,12 +1154,6 @@ int main(int argc, char *const argv[])
case 'r':
reset = 1;
break;
case 'L':
load = 1;
break;
case 'N':
load = 0;
break;
case 'q':
verbosity = 0;
break;
@ -1410,12 +1340,6 @@ int main(int argc, char *const argv[])
}
}
/* Force load if tuning, otherwise consider option. */
if (load > 0 || tuning) {
load = 1;
create_load(&loadgen);
}
time(&start_time);
if (!tuning) {
@ -1455,8 +1379,5 @@ int main(int argc, char *const argv[])
(int)(time(NULL) - start_time));
}
if (load > 0)
pthread_cancel(loadgen);
return 0;
}