[PATCH v3] tst-{pthread|sched}-affinity-inheritance: Only use in-mask CPUs in affinity mask.
Stefan Liebler
stli@linux.ibm.com
Thu Feb 5 12:03:08 GMT 2026
On s390x, the two tests are failing on a lpar with linux 6.18 booted with nosmt:
FAIL: misc/tst-sched-affinity-inheritance
FAIL: nptl/tst-pthread-affinity-inheritance
Both tests were failing because they are claiming that the CPU affinity mask was
not correctly inherited in the forked process/thread.
The error already happened before forking, as the mask was set up to use
CPUs 0-14 in set_cpu_mask(). But according to e.g. lscpu or the line
"Cpus_allowed_list" in /proc/self/status, only the following CPUs were in mask at startup:
0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30
while 1, 3, 5, ... were configured, but not online.
Now the test first gets the current CPU mask at startup in do_test() and
set_cpu_mask() only selects those available CPUs. The test is now just
counting the available CPUs instead of relying on get_nprocs(). This allows
to run the test even if it was already limited via taskset.
Therefore both concrete tests now have the get_my_affinity() function. This
also allows to implement verify_my_affinity() in the common skeleton.
In order to ensure that the affinity mask is really set as expected,
verify_my_affinity() is now also called before forking a new process or
creating a new thread.
For also printing the list of mismatched CPU IDs in xor_set in
verify_my_affinity(), the argument order of CPU_ISSET_S is now fixed.
Furthermore we now keep iterating over all configured CPUs to print
the list of cpucount IDs instead of iterating over the first nproc CPUs.
---
nptl/tst-pthread-affinity-inheritance.c | 41 ++--------
nptl/tst-skeleton-affinity-inheritance.c | 77 +++++++++++++++----
.../linux/tst-sched-affinity-inheritance.c | 40 ++--------
3 files changed, 76 insertions(+), 82 deletions(-)
diff --git a/nptl/tst-pthread-affinity-inheritance.c b/nptl/tst-pthread-affinity-inheritance.c
index 153fc904df..9396256ff9 100644
--- a/nptl/tst-pthread-affinity-inheritance.c
+++ b/nptl/tst-pthread-affinity-inheritance.c
@@ -25,48 +25,19 @@
#include <support/check.h>
static void
-set_my_affinity (size_t size, const cpu_set_t *set)
+get_my_affinity (size_t size, cpu_set_t *set)
{
- int ret = pthread_setaffinity_np (pthread_self (), size, set);
-
+ int ret = pthread_getaffinity_np (pthread_self (), size, set);
if (ret != 0)
- FAIL ("pthread_setaffinity_np returned %d (%s)", ret, strerror (ret));
+ FAIL ("pthread_getaffinity_np returned %d (%s)", ret, strerror (ret));
}
static void
-verify_my_affinity (int nproc, int nproc_configured, size_t size,
- const cpu_set_t *expected_set)
+set_my_affinity (size_t size, const cpu_set_t *set)
{
- cpu_set_t *set = CPU_ALLOC (nproc_configured);
- cpu_set_t *xor_set = CPU_ALLOC (nproc_configured);
-
- if (set == NULL || xor_set== NULL)
- FAIL_EXIT1 ("verify_my_affinity: Failed to allocate cpuset: %m\n");
-
- int ret = pthread_getaffinity_np (pthread_self (), size, set);
+ int ret = pthread_setaffinity_np (pthread_self (), size, set);
if (ret != 0)
- FAIL ("pthread_getaffinity_np returned %d (%s)", ret, strerror (ret));
-
- CPU_XOR_S (size, xor_set, expected_set, set);
-
- int cpucount = CPU_COUNT_S (size, xor_set);
-
- if (cpucount > 0)
- {
- FAIL ("Affinity mask not inherited, "
- "following %d CPUs mismatched in the expected and actual sets: ",
- cpucount);
- for (int cur = 0; cur < nproc && cpucount >= 0; cur++)
- if (CPU_ISSET_S (size, cur, xor_set))
- {
- printf ("%d ", cur);
- cpucount--;
- }
- printf ("\n");
- }
-
- CPU_FREE (set);
- CPU_FREE (xor_set);
+ FAIL ("pthread_setaffinity_np returned %d (%s)", ret, strerror (ret));
}
#include "tst-skeleton-affinity-inheritance.c"
diff --git a/nptl/tst-skeleton-affinity-inheritance.c b/nptl/tst-skeleton-affinity-inheritance.c
index e1f328ae26..f53805de42 100644
--- a/nptl/tst-skeleton-affinity-inheritance.c
+++ b/nptl/tst-skeleton-affinity-inheritance.c
@@ -42,9 +42,9 @@
struct test_param
{
- int nproc;
int nproc_configured;
cpu_set_t *set;
+ cpu_set_t *set_at_startup;
size_t size;
bool entry;
};
@@ -52,18 +52,61 @@ struct test_param
void __attribute__((noinline))
set_cpu_mask (struct test_param *param, bool entry)
{
- int cpus = param->nproc;
+ /* Do not determine the number of CPUs based on get_nproc as the test process
+ could already be taskset to less CPUs. */
+ int cpus = CPU_COUNT_S (param->size, param->set_at_startup);
/* Less CPUS for the first level, if that's possible. */
if (entry && cpus > 1)
cpus--;
+ /* Only use CPUs which were in mask at start of the test process. */
CPU_ZERO_S (param->size, param->set);
- while (cpus > 0)
- CPU_SET_S (--cpus, param->size, param->set);
+ for (int cur = 0; cpus > 0; cur++)
+ {
+ if (CPU_ISSET_S (cur, param->size, param->set_at_startup))
+ {
+ CPU_SET_S (cur, param->size, param->set);
+ cpus--;
+ }
+ }
+
+ if (cpus != 0)
+ FAIL_EXIT1 ("Failed to add all requested CPUs to the affinity set\n");
+}
+
+static void
+verify_my_affinity (int nproc_configured, size_t size,
+ const cpu_set_t *expected_set)
+{
+ cpu_set_t *set = CPU_ALLOC (nproc_configured);
+ cpu_set_t *xor_set = CPU_ALLOC (nproc_configured);
+
+ if (set == NULL || xor_set == NULL)
+ FAIL_EXIT1 ("verify_my_affinity: Failed to allocate cpuset: %m\n");
- if (CPU_COUNT_S (param->size, param->set) == 0)
- FAIL_EXIT1 ("Failed to add any CPUs to the affinity set\n");
+ get_my_affinity (size, set);
+
+ CPU_XOR_S (size, xor_set, expected_set, set);
+
+ int cpucount = CPU_COUNT_S (size, xor_set);
+
+ if (cpucount > 0)
+ {
+ FAIL ("Affinity mask not inherited, "
+ "following %d CPUs mismatched in the expected and actual sets:\n",
+ cpucount);
+ for (int cur = 0; cpucount > 0; cur++)
+ if (CPU_ISSET_S (cur, size, xor_set))
+ {
+ printf ("%d ", cur);
+ cpucount--;
+ }
+ printf ("\n");
+ }
+
+ CPU_FREE (set);
+ CPU_FREE (xor_set);
}
static void *
@@ -72,8 +115,7 @@ child_test (void *arg)
struct test_param *param = arg;
printf ("%d:%d child\n", getpid (), gettid ());
- verify_my_affinity (param->nproc, param->nproc_configured, param->size,
- param->set);
+ verify_my_affinity (param->nproc_configured, param->size, param->set);
return NULL;
}
@@ -91,13 +133,15 @@ do_one_test (void *arg)
child = do_one_test;
set_cpu_mask (param, true);
set_my_affinity (param->size, param->set);
+ /* Ensure that the affinity mask is really set as expected before forking
+ a new process or creating a new thread. */
+ verify_my_affinity (param->nproc_configured, param->size, param->set);
param->entry = false;
}
else
{
/* Verification for the first level. */
- verify_my_affinity (param->nproc, param->nproc_configured, param->size,
- param->set);
+ verify_my_affinity (param->nproc_configured, param->size, param->set);
/* Launch the second level test, launching CHILD_TEST as a subprocess and
then as a subthread. Use a different mask to see if it gets
@@ -136,23 +180,30 @@ do_test (void)
/* Large enough in case the kernel decides to return the larger mask. This
seems to happen on some kernels for S390x. */
int num_configured_cpus = get_nprocs_conf ();
- int num_cpus = get_nprocs ();
struct test_param param =
{
- .nproc = num_cpus,
.nproc_configured = num_configured_cpus,
.set = CPU_ALLOC (num_configured_cpus),
+ .set_at_startup = CPU_ALLOC (num_configured_cpus),
.size = CPU_ALLOC_SIZE (num_configured_cpus),
.entry = true,
};
if (param.set == NULL)
- FAIL_EXIT1 ("error: CPU_ALLOC (%d) failed\n", num_cpus);
+ FAIL_EXIT1 ("error: CPU_ALLOC (%d) for param.set failed\n",
+ num_configured_cpus);
+ if (param.set_at_startup == NULL)
+ FAIL_EXIT1 ("error: CPU_ALLOC (%d) for param.set_at_startup failed\n",
+ num_configured_cpus);
+
+ /* Get a list of all available CPUs for this test. */
+ get_my_affinity (param.size, param.set_at_startup);
do_one_test (¶m);
CPU_FREE (param.set);
+ CPU_FREE (param.set_at_startup);
return 0;
}
diff --git a/sysdeps/unix/sysv/linux/tst-sched-affinity-inheritance.c b/sysdeps/unix/sysv/linux/tst-sched-affinity-inheritance.c
index 8a42d275fc..09e17cbdec 100644
--- a/sysdeps/unix/sysv/linux/tst-sched-affinity-inheritance.c
+++ b/sysdeps/unix/sysv/linux/tst-sched-affinity-inheritance.c
@@ -25,48 +25,20 @@
#include <support/check.h>
static void
-set_my_affinity (size_t size, const cpu_set_t *set)
+get_my_affinity (size_t size, cpu_set_t *set)
{
- int ret = sched_setaffinity (0, size, set);
-
+ int ret = sched_getaffinity (0, size, set);
if (ret != 0)
- FAIL ("sched_setaffinity returned %d (%s)", ret, strerror (ret));
+ FAIL ("sched_getaffinity returned %d (%s)", ret, strerror (ret));
}
static void
-verify_my_affinity (int nproc, int nproc_configured, size_t size,
- const cpu_set_t *expected_set)
+set_my_affinity (size_t size, const cpu_set_t *set)
{
- cpu_set_t *set = CPU_ALLOC (nproc_configured);
- cpu_set_t *xor_set = CPU_ALLOC (nproc_configured);
-
- if (set == NULL || xor_set== NULL)
- FAIL_EXIT1 ("verify_my_affinity: Failed to allocate cpuset: %m\n");
+ int ret = sched_setaffinity (0, size, set);
- int ret = sched_getaffinity (0, size, set);
if (ret != 0)
- FAIL ("sched_getaffinity returned %d (%s)", ret, strerror (ret));
-
- CPU_XOR_S (size, xor_set, expected_set, set);
-
- int cpucount = CPU_COUNT_S (size, xor_set);
-
- if (cpucount > 0)
- {
- FAIL ("Affinity mask not inherited, "
- "following %d CPUs mismatched in the expected and actual sets:\n",
- cpucount);
- for (int cur = 0; cur < nproc && cpucount >= 0; cur++)
- if (CPU_ISSET_S (size, cur, xor_set))
- {
- printf ("%d ", cur);
- cpucount--;
- }
- printf ("\n");
- }
-
- CPU_FREE (set);
- CPU_FREE (xor_set);
+ FAIL ("sched_setaffinity returned %d (%s)", ret, strerror (ret));
}
#include <nptl/tst-skeleton-affinity-inheritance.c>
--
2.52.0
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