igt: Exercise the shrinker

Introduce a new fork helper that spawns a process that just repeatedly
calls i915_gem_shrink_all() and watch what happens as we try to use
objects that have been shrunk.

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>

1 files changed, 22 insertions, 0 deletions

diff --git a/lib/igt_debugfs.c b/lib/igt_debugfs.c
index e64d001b..0a991a1f 100644
--- a/lib/igt_debugfs.c
+++ b/lib/igt_debugfs.c
@@ -873,6 +873,28 @@ void igt_pipe_crc_collect_crc(igt_pipe_crc_t *pipe_crc, igt_crc_t *out_crc)
  */
 
 /**
+ * igt_drop_caches_has:
+ * @val: bitmask for DROP_* values
+ *
+ * This queries the debugfs to see if it supports the full set of desired
+ * operations.
+ */
+bool igt_drop_caches_has(uint64_t val)
+{
+	FILE *file;
+	uint64_t mask;
+
+	mask = 0;
+	file = igt_debugfs_fopen("i915_gem_drop_caches", "r");
+	if (file) {
+		fscanf(file, "0x%" PRIx64, &mask);
+		fclose(file);
+	}
+
+	return (val & mask) == val;
+}
+
+/**
  * igt_drop_caches_set:
  * @val: bitmask for DROP_* values
  *