drm/i915: Preallocate enough space for the average request
Rather than being interrupted when we run out of space halfway through
the request, and having to restart from the beginning (and returning to
userspace), flush a little more free space when we prepare the request.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1461833819-3991-15-git-send-email-chris@chris-wilson.co.uk
diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
index 4139858..4dedeaa 100644
--- a/drivers/gpu/drm/i915/intel_lrc.c
+++ b/drivers/gpu/drm/i915/intel_lrc.c
@@ -700,6 +700,12 @@
{
int ret;
+ /* Flush enough space to reduce the likelihood of waiting after
+ * we start building the request - in which case we will just
+ * have to repeat work.
+ */
+ request->reserved_space += MIN_SPACE_FOR_ADD_REQUEST;
+
request->ringbuf = request->ctx->engine[request->engine->id].ringbuf;
if (i915.enable_guc_submission) {
@@ -725,6 +731,7 @@
if (ret)
goto err_unpin;
+ request->reserved_space -= MIN_SPACE_FOR_ADD_REQUEST;
return 0;
err_unpin: