| Message ID | 20250228-mm-selftests-v3-6-958e3b6f0203@google.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | selftests/mm: Some cleanups from trying to run them | expand |
On 28/02/25 10:24 pm, Brendan Jackman wrote: > This calculation divides a fixed parameter by an environment-dependent > parameter i.e. the number of CPUs. > > The simple way to avoid machine-specific failures here is to just put a > cap on the max value of the latter. > > Suggested-by: Mateusz Guzik <mjguzik@gmail.com> > Signed-off-by: Brendan Jackman <jackmanb@google.com> > --- Reviewed-by: Dev Jain <dev.jain@arm.com>
On Fri, 28 Feb 2025 at 17:55, Brendan Jackman <jackmanb@google.com> wrote: > > This calculation divides a fixed parameter by an environment-dependent > parameter i.e. the number of CPUs. > > The simple way to avoid machine-specific failures here is to just put a > cap on the max value of the latter. > > Suggested-by: Mateusz Guzik <mjguzik@gmail.com> > Signed-off-by: Brendan Jackman <jackmanb@google.com> > --- > tools/testing/selftests/mm/uffd-stress.c | 11 ++++++++++- > 1 file changed, 10 insertions(+), 1 deletion(-) > > diff --git a/tools/testing/selftests/mm/uffd-stress.c b/tools/testing/selftests/mm/uffd-stress.c > index efe2051c393096e237d942c04a264b6611a6e127..5656128590373ed376b3b5d9259e5ca3867a4099 100644 > --- a/tools/testing/selftests/mm/uffd-stress.c > +++ b/tools/testing/selftests/mm/uffd-stress.c > @@ -434,6 +434,7 @@ static void sigalrm(int sig) > > int main(int argc, char **argv) > { > + unsigned long nr_cpus; > size_t bytes; > > if (argc < 4) > @@ -452,7 +453,15 @@ int main(int argc, char **argv) > return KSFT_SKIP; > } > > - nr_threads = sysconf(_SC_NPROCESSORS_ONLN); > + nr_cpus = sysconf(_SC_NPROCESSORS_ONLN); > + if (nr_cpus > 32) { > + /* Don't let calculation below go to zero. */ > + ksft_print_msg("_SC_NPROCESSORS_ONLN (%lu) too large, capping nr_threads to 32\n", > + nr_cpus); > + nr_threads = 32; > + } else { > + nr_cpus = nr_threads; Won't have time to send v4 for a few days so I'll just note here: this shoudl be nr_thread = nr_cpus. This causes a division by zero on machines with less than 30 CPUs.
diff --git a/tools/testing/selftests/mm/uffd-stress.c b/tools/testing/selftests/mm/uffd-stress.c index efe2051c393096e237d942c04a264b6611a6e127..5656128590373ed376b3b5d9259e5ca3867a4099 100644 --- a/tools/testing/selftests/mm/uffd-stress.c +++ b/tools/testing/selftests/mm/uffd-stress.c @@ -434,6 +434,7 @@ static void sigalrm(int sig) int main(int argc, char **argv) { + unsigned long nr_cpus; size_t bytes; if (argc < 4) @@ -452,7 +453,15 @@ int main(int argc, char **argv) return KSFT_SKIP; } - nr_threads = sysconf(_SC_NPROCESSORS_ONLN); + nr_cpus = sysconf(_SC_NPROCESSORS_ONLN); + if (nr_cpus > 32) { + /* Don't let calculation below go to zero. */ + ksft_print_msg("_SC_NPROCESSORS_ONLN (%lu) too large, capping nr_threads to 32\n", + nr_cpus); + nr_threads = 32; + } else { + nr_cpus = nr_threads; + } nr_pages_per_cpu = bytes / page_size / nr_threads; if (!nr_pages_per_cpu) {
This calculation divides a fixed parameter by an environment-dependent parameter i.e. the number of CPUs. The simple way to avoid machine-specific failures here is to just put a cap on the max value of the latter. Suggested-by: Mateusz Guzik <mjguzik@gmail.com> Signed-off-by: Brendan Jackman <jackmanb@google.com> --- tools/testing/selftests/mm/uffd-stress.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-)