HI !
minor bug in cyclictest but potential causing confusion on cyclictest
resuults when running as non-root user.
Setup:
if one sets the rtprio in /etc/security/limits.conf to something below
prio max - like:
@hofrat hard rtprio 10
@hofrat soft rtprio 10
but then starts cylictest with -p 80 cyclictest will not fuss and also
display priority 80 (as it uses par->prio in print_stat) but effectively
runs with prio 0 as the return value of sched_setscheduler is not being
checked in timerthread), resulting in semingly bad scheduling jitter values.
So maybe cyclictest should take the effective maximum schduling priority
of the user and not the scheduling policy maximum. Not sur if the check
in timerthread is actually really needed - but it should not hurt ither.
patch below (against current git) at "works for me" quality.
thx!
hofrat
diff --git a/src/cyclictest/cyclictest.c b/src/cyclictest/cyclictest.c
index 731b4bd..fa89502 100644
--- a/src/cyclictest/cyclictest.c
+++ b/src/cyclictest/cyclictest.c
@@ -33,6 +33,7 @@
#include <sys/time.h>
#include <sys/utsname.h>
#include <sys/mman.h>
+#include <sys/resource.h>
#include "rt_numa.h"
#include "rt-utils.h"
@@ -641,7 +642,10 @@ void *timerthread(void *param)
memset(&schedp, 0, sizeof(schedp));
schedp.sched_priority = par->prio;
- sched_setscheduler(0, par->policy, &schedp);
+ if(sched_setscheduler(0, par->policy, &schedp) == -1){
+ fprintf(stderr,"sched_setscheduler prio %d failed\n",par->prio);
+ par->prio=0;
+ }
/* Get current time */
clock_gettime(par->clock, &now);
@@ -943,6 +947,7 @@ static void process_options (int argc, char *argv[])
{
int error = 0;
int max_cpus = sysconf(_SC_NPROCESSORS_CONF);
+ struct rlimit rlim;
for (;;) {
int option_index = 0;
@@ -1145,6 +1150,15 @@ static void process_options (int argc, char *argv[])
policy = SCHED_FIFO;
}
+ /* check against rlimit see /etc/security/limits.conf */
+ getrlimit(RLIMIT_RTPRIO, &rlim);
+ if ( priority > rlim.rlim_max){
+ fprintf(stderr, "defaulting realtime priority to %d\n",
+ (int) rlim.rlim_max);
+ priority = rlim.rlim_max;
+ }
+
+
if ((policy == SCHED_FIFO || policy == SCHED_RR) && priority == 0) {
fprintf(stderr, "defaulting realtime priority to %d\n",
num_threads+1);
--
To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
