[Intel-gfx] [PATCH i-g-t v2 2/8] lib/igt_gt: add intel_measure_ring_size

[Daniele Ceraolo Spurio]

The logic to measure the ring size is replicated almost identically in
several tests. Adding it as a common function will make the code
cleaner.

The tests are updated in follow up patches.

Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio at intel.com>
Cc: Chris Wilson <chris at chris-wilson.co.uk>
---
 lib/igt_gt.c | 83 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 lib/igt_gt.h |  2 ++
 2 files changed, 85 insertions(+)

diff --git a/lib/igt_gt.c b/lib/igt_gt.c
index 89727d2..76fdbc5 100644
--- a/lib/igt_gt.c
+++ b/lib/igt_gt.c
@@ -40,6 +40,7 @@
 #include "ioctl_wrappers.h"
 #include "intel_reg.h"
 #include "intel_chipset.h"
+#include "igt_dummyload.h"
 
 /**
  * SECTION:igt_gt
@@ -577,6 +578,88 @@ unsigned intel_detect_and_clear_missed_interrupts(int fd)
 	return missed;
 }
 
+static void alarm_handler(int sig)
+{
+}
+
+/**
+ * intel_measure_ring_size:
+ * @fd: open i915 drm file descriptor
+ * @engine: execbuf engine flag
+ * @new_ctx: use a new context to account for the space used by the lrc init
+ *
+ * This function calculates the maximum number of batches that can be inserted
+ * at the same time in the ring on the selected engine.
+ *
+ * Returns:
+ * Number of batches that fit in the ring
+ */
+unsigned int intel_measure_ring_size(int fd, unsigned int engine, bool new_ctx)
+{
+	struct sigaction old_sa, sa = { .sa_handler = alarm_handler };
+	struct drm_i915_gem_exec_object2 obj[2];
+	struct drm_i915_gem_execbuffer2 execbuf;
+	const uint32_t bbe = MI_BATCH_BUFFER_END;
+	unsigned int count, last;
+	struct itimerval itv;
+	struct igt_cork cork;
+
+	igt_require_intel(fd);
+
+	memset(obj, 0, sizeof(obj));
+	obj[1].handle = gem_create(fd, 4096);
+	gem_write(fd, obj[1].handle, 0, &bbe, sizeof(bbe));
+
+	memset(&execbuf, 0, sizeof(execbuf));
+	execbuf.buffers_ptr = to_user_pointer(&obj[1]);
+	execbuf.buffer_count = 1;
+	execbuf.flags = engine;
+	gem_execbuf(fd, &execbuf);
+	gem_sync(fd, obj[1].handle);
+
+	obj[0].handle = igt_cork_plug(fd, &cork);
+
+	execbuf.buffers_ptr = to_user_pointer(obj);
+	execbuf.buffer_count = 2;
+
+	if (new_ctx)
+		execbuf.rsvd1 = gem_context_create(fd);
+
+	sigaction(SIGALRM, &sa, &old_sa);
+	itv.it_interval.tv_sec = 0;
+	itv.it_interval.tv_usec = 100;
+	itv.it_value.tv_sec = 0;
+	itv.it_value.tv_usec = 1000;
+	setitimer(ITIMER_REAL, &itv, NULL);
+
+	last = -1;
+	count = 0;
+	do {
+		if (ioctl(fd, DRM_IOCTL_I915_GEM_EXECBUFFER2, &execbuf) == 0) {
+			count++;
+			continue;
+		}
+
+		if (last == count)
+			break;
+
+		last = count;
+	} while (1);
+
+	memset(&itv, 0, sizeof(itv));
+	setitimer(ITIMER_REAL, &itv, NULL);
+	sigaction(SIGALRM, &old_sa, NULL);
+
+	igt_cork_unplug(&cork);
+	gem_close(fd, obj[0].handle);
+	gem_close(fd, obj[1].handle);
+
+	if (new_ctx)
+		gem_context_destroy(fd, execbuf.rsvd1);
+
+	return count;
+}
+
 const struct intel_execution_engine intel_execution_engines[] = {
 	{ "default", NULL, 0, 0 },
 	{ "render", "rcs0", I915_EXEC_RENDER, 0 },
diff --git a/lib/igt_gt.h b/lib/igt_gt.h
index 2579cbd..4e4fc01 100644
--- a/lib/igt_gt.h
+++ b/lib/igt_gt.h
@@ -63,6 +63,8 @@ void igt_clflush_range(void *addr, int size);
 
 unsigned intel_detect_and_clear_missed_interrupts(int fd);
 
+unsigned int intel_measure_ring_size(int fd, unsigned int engine, bool new_ctx);
+
 extern const struct intel_execution_engine {
 	const char *name;
 	const char *full_name;
-- 
1.9.1