On 6/15/22 13:38, Sebastian Andrzej Siewior wrote:
Assuming the current affinity mask of the task is 0x31 (CPUs 0, 4, 5).
Starting cyclictest with '-S' option will fork the following threads:
- monitor, mask 0x31
- measure thread 1, mask 0x01
- measure thread 2, mask 0x10
- measure thread 3, mask 0x20
works as expected. Using the options '-S --mainaffinity=0' leads to:
- monitor, mask 0x01
- measure thread 1, mask 0x01
- measure thread 2, mask 0x01
- measure thread 3, mask 0x01
because the mask of the main thread has been reset early to 0x01 and
does not allow a CPU mask outside of this mask while setting the
affinity for the new threads.
Delay setting the affinity of the main/ monitor thread after the
measuring threads have been deployed. This leads to the following
state:
- monitor, mask 0x01
- measure thread 1, mask 0x01
- measure thread 2, mask 0x10
- measure thread 3, mask 0x20
Signed-off-by: Sebastian Andrzej Savior <bigeasy@xxxxxxxxxxxxx>
---
src/cyclictest/cyclictest.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
diff --git a/src/cyclictest/cyclictest.c b/src/cyclictest/cyclictest.c
index be8285a072b4e..cbf8d00293ec6 100644
--- a/src/cyclictest/cyclictest.c
+++ b/src/cyclictest/cyclictest.c
@@ -1816,10 +1816,7 @@ int main(int argc, char **argv)
printf("Online CPUs = %d\n", online_cpus);
}
- /* Restrict the main pid to the affinity specified by the user */
- if (main_affinity_mask != NULL) {
- set_main_thread_affinity(main_affinity_mask);
- } else if (affinity_mask != NULL) {
+ if (affinity_mask != NULL) {
set_main_thread_affinity(affinity_mask);
2 other remarks (sorry for the spam):
- In the documentation, '-a' seems to indicate a mask for the threads, not for
the main process. Should the main thread be restricted to the mask obtained
for '-a' ?
- I think there is a bug (unrelated to the patch) when issuing:
./cyclictest -l20000 -v -a -t10
This is due to trying to print a NULL the affinity_mask at:
@@ -1088,9 +1093,6 @@ static void process_options(int argc, char *argv[], int max_cpus)
if (setaffinity == AFFINITY_SPECIFIED && !affinity_mask)
display_help(1);
- if (verbose)
- printf("Using %u cpus.\n",
- numa_bitmask_weight(affinity_mask));
break;
case 'A':
case OPT_ALIGNED:
The command:
./cyclictest -l20000 -a -t10 -v
will work since '-v' is parsed at last and the 'if (verbose)' statement
is ignored.
if (verbose)
printf("Using %u cpus.\n",
@@ -2094,6 +2091,10 @@ int main(int argc, char **argv)
fatal("failed to create thread %d: %s\n", i, strerror(status));
}
+ /* Restrict the main pid to the affinity specified by the user */
+ if (main_affinity_mask != NULL)
+ set_main_thread_affinity(main_affinity_mask);
+
if (use_fifo) {
status = pthread_create(&fifo_threadid, NULL, fifothread, NULL);
if (status)
