The core scheduling is for smt enabled cpus. It is not returns failure and gives plenty of error messages and not clearly points to the smt issue if the smt is disabled. It just mention "not a core sched system" and many other messages. For example:

Not a core sched system tid=210574, / tgid=210574 / pgid=210574: ffffffffffffffff Not a core sched system tid=210575, / tgid=210575 / pgid=210574: ffffffffffffffff Not a core sched system tid=210577, / tgid=210575 / pgid=210574: ffffffffffffffff

(similar things many other times)

In this patch, the test will first read /sys/devices/system/cpu/smt/active, if the file cannot be opened or its value is 0, the test is skipped with an explanatory message. This helps developers understand why it is skipped and avoids unnecessary attention when running the full selftest suite.

Signed-off-by: Yifei Liu yifei.l.liu@oracle.com --- tools/testing/selftests/sched/cs_prctl_test.c | 23 ++++++++++++++++++- 1 file changed, 22 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/sched/cs_prctl_test.c b/tools/testing/selftests/sched/cs_prctl_test.c index 52d97fae4dbd..7ce8088cde6a 100644 --- a/tools/testing/selftests/sched/cs_prctl_test.c +++ b/tools/testing/selftests/sched/cs_prctl_test.c @@ -32,6 +32,8 @@ #include <stdlib.h> #include <string.h>

+#include "../kselftest.h" + #if __GLIBC_PREREQ(2, 30) == 0 #include <sys/syscall.h> static pid_t gettid(void) @@ -109,6 +111,22 @@ static void handle_usage(int rc, char *msg) exit(rc); }

+int check_smt(void) +{ + int c = 0; + FILE *file; + + file = fopen("/sys/devices/system/cpu/smt/active", "r"); + if (!file) + return 0; + c = fgetc(file) - 0x30; + fclose(file); + if (c == 0 || c == 1) + return c; + //if fgetc returns EOF or -1 for correupted files, return 0. + return 0; +} + static unsigned long get_cs_cookie(int pid) { unsigned long long cookie; @@ -271,7 +289,10 @@ int main(int argc, char *argv[]) delay = -1;

srand(time(NULL)); - + if (!check_smt()) { + ksft_test_result_skip("smt not enabled\n"); + return 1; + } /* put into separate process group */ if (setpgid(0, 0) != 0) handle_error("process group");