tests/perf_pmu: Handle CPU hotplug failures better

CPU hotplug, especially CPU0, can be flaky on commodity hardware.

To improve test reliability and reponse times when testing larger runs we
need to handle those cases better.

Handle failures to off-line a CPU by immediately skipping the test, and
failures to on-line a CPU by immediately rebooting the machine.

This patch includes igt_sysrq_reboot implementation from Chris Wilson.

v2: Halt by default, reboot if env variable IGT_REBOOT_ON_FATAL_ERROR is
    set. (Petri Latvala)

v3: Add missign docs and update stale comment. (Petri Latvala)

v4: Use pause instead of sleep. (Chris Wilson)
v5: Newlines! (Chris Wilson)

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Petri Latvala <petri.latvala@intel.com>
Cc: Tomi Sarvela <tomi.p.sarvela@intel.com>
Reviewed-by: Petri Latvala <petri.latvala@intel.com>

1 files changed, 27 insertions, 0 deletions

diff --git a/lib/igt_sysrq.c b/lib/igt_sysrq.c
new file mode 100644
index 00000000..3bda321f
--- /dev/null
+++ b/lib/igt_sysrq.c
@@ -0,0 +1,27 @@
+#include <unistd.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <sys/reboot.h>
+
+#include "igt_core.h"
+
+#include "igt_sysrq.h"
+
+/**
+ * igt_sysrq_reboot: Reboots the machine
+ *
+ * Syncs filesystems and immediately reboots the machine.
+ */
+void igt_sysrq_reboot(void)
+{
+	sync();
+
+	/* Try to be nice at first, and if that fails pull the trigger */
+	if (reboot(RB_AUTOBOOT)) {
+		int fd = open("/proc/sysrq-trigger", O_WRONLY);
+		igt_ignore_warn(write(fd, "b", 2));
+		close(fd);
+	}
+
+	abort();
+}