Tests: Introduce conf_proc_count()

Tests are using the nproc utility which return the number of
_available_ CPUs. The distinction between online, available and
configured CPUs is subtle, but important.

The number of "online" CPUs can change at runtime as CPUs are
hot-plugged. This could happen during a test and result in
unexpected results.

The number of "configured" CPUs includes any CPU which may be
offline at the time.

The number of "available" CPUs, which is what is returned by the
nproc utility, may differ from both "online" and "configured"
counts. This is the case in containers which are assigned to a
subset of configured CPUs.

Signed-off-by: Jérémie Galarneau <jeremie.galarneau@efficios.com>

diff --git a/tests/utils/utils.sh b/tests/utils/utils.sh
index 35207929eca6afd63394c63a7f7d556c579f3489..0817e65bbd90dd344b05d14f9d2baaaa8b1e9212 100644 (file)
--- a/tests/utils/utils.sh
+++ b/tests/utils/utils.sh
@@ -86,6 +86,16 @@ function randstring()
        echo
 }
 
+# Return the number of _configured_ CPUs.
+function conf_proc_count()
+{
+       getconf _NPROCESSORS_CONF
+       if [ $? -ne 0 ]; then
+               diag "Failed to get the number of configured CPUs"
+       fi
+       echo
+}
+
 function enable_kernel_lttng_event
 {
        local expected_to_fail="$1"