Cyclictest assumes online CPUs are numbered 0-N with no "holes". This
causes it to silently set CPU affinity incorrectly if a CPU is offline
that isn't at the end of the CPU numbering. Read the online status of
a CPU through sysfs before attempting to run a thread on that CPU to
prevent this problem.
Signed-off-by: Allen Martin <amartin@xxxxxxxxxx>
---
src/cyclictest/cyclictest.c | 52 +++++++++++++++++++++++++++++++++++++--------
1 file changed, 43 insertions(+), 9 deletions(-)
diff --git a/src/cyclictest/cyclictest.c b/src/cyclictest/cyclictest.c
index 568e52f4b328..80013a91962e 100644
--- a/src/cyclictest/cyclictest.c
+++ b/src/cyclictest/cyclictest.c
@@ -958,6 +958,27 @@ static int has_smi_counter(void)
}
#endif
+/* Check if a CPU is online by reading from sysfs */
+static int cpu_is_online(int cpunum)
+{
+ char path[PATH_MAX];
+ FILE *fp;
+ int online = 1;
+
+ snprintf(path, sizeof(path), "/sys/devices/system/cpu/cpu%d/online",
+ cpunum);
+ /* if CPU has no online toggle it must always be online */
+ if (access(path, F_OK) != 0)
+ return 1;
+ fp = fopen(path, "r");
+ if (!fp)
+ return 1;
+ fscanf(fp, "%d", &online);
+ fclose(fp);
+
+ return online;
+}
+
/*
* timer thread
*
@@ -1515,7 +1536,8 @@ enum option_values {
};
/* Process commandline options */
-static void process_options (int argc, char *argv[], int max_cpus)
+static void process_options (int argc, char *argv[], int max_cpus,
+ int online_cpus)
{
int error = 0;
int option_affinity = 0;
@@ -1721,7 +1743,7 @@ static void process_options (int argc, char *argv[], int max_cpus)
if (numa)
fatal("numa and smp options are mutually exclusive\n");
smp = 1;
- num_threads = max_cpus;
+ num_threads = online_cpus;
setaffinity = AFFINITY_USEALL;
break;
case 't':
@@ -1735,7 +1757,7 @@ static void process_options (int argc, char *argv[], int max_cpus)
else if (optind<argc && atoi(argv[optind]))
num_threads = atoi(argv[optind]);
else
- num_threads = max_cpus;
+ num_threads = online_cpus;
break;
case OPT_TRIGGER:
trigger = atoi(optarg);
@@ -1759,7 +1781,7 @@ static void process_options (int argc, char *argv[], int max_cpus)
fatal("numa and smp options are mutually exclusive\n");
numa_on_and_available();
#ifdef NUMA
- num_threads = max_cpus;
+ num_threads = online_cpus;
setaffinity = AFFINITY_USEALL;
#else
warn("cyclictest was not built with the numa option\n");
@@ -2206,17 +2228,20 @@ int main(int argc, char **argv)
sigset_t sigset;
int signum = SIGALRM;
int mode;
- int max_cpus = sysconf(_SC_NPROCESSORS_ONLN);
+ int max_cpus = sysconf(_SC_NPROCESSORS_CONF);
+ int online_cpus = sysconf(_SC_NPROCESSORS_ONLN);
int i, ret = -1;
int status;
- process_options(argc, argv, max_cpus);
+ process_options(argc, argv, max_cpus, online_cpus);
if (check_privs())
exit(EXIT_FAILURE);
- if (verbose)
+ if (verbose) {
printf("Max CPUs = %d\n", max_cpus);
+ printf("Online CPUs = %d\n", online_cpus);
+ }
if (trigger) {
int retval;
@@ -2368,6 +2393,10 @@ int main(int argc, char **argv)
int node;
struct thread_param *par;
struct thread_stat *stat;
+ static int cpu_num = 0;
+
+ while (!cpu_is_online(cpu_num))
+ cpu_num++;
status = pthread_attr_init(&attr);
if (status != 0)
@@ -2468,12 +2497,17 @@ int main(int argc, char **argv)
switch (setaffinity) {
case AFFINITY_UNSPECIFIED: par->cpu = -1; break;
case AFFINITY_SPECIFIED:
- par->cpu = cpu_for_thread(i, max_cpus);
+ par->cpu = cpu_for_thread(cpu_num++, max_cpus);
+ if (verbose)
+ printf("Thread %d using cpu %d.\n", i,
+ par->cpu);
+ break;
+ case AFFINITY_USEALL:
+ par->cpu = cpu_num++ % max_cpus;
if (verbose)
printf("Thread %d using cpu %d.\n", i,
par->cpu);
break;
- case AFFINITY_USEALL: par->cpu = i % max_cpus; break;
}
stat->min = 1000000;
stat->max = 0;
--
2.11.0
--
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