From 0e34c02dd60f8d301a1b4c1bbcd3c90ee05bdb0a Mon Sep 17 00:00:00 2001
From: Matthew Marsh <matt@stonethree.com>
Date: Tue, 22 Dec 2015 11:10:31 +0200
Subject: [PATCH] nvenc: fix high CPU use on initialization of multiple
 encoders at the same time

We need a static lock to protect various NVENC methods in _set_format(). Without
this the CPU use increases dramatically on initialisation of the element when
there are multiple elements being initialised at the same time.

https://bugzilla.gnome.org/show_bug.cgi?id=759742
---
 sys/nvenc/gstnvbaseenc.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/sys/nvenc/gstnvbaseenc.c b/sys/nvenc/gstnvbaseenc.c
index ccf7186a97..8e5b088269 100644
--- a/sys/nvenc/gstnvbaseenc.c
+++ b/sys/nvenc/gstnvbaseenc.c
@@ -70,6 +70,11 @@ enum
   PROP_DEVICE_ID,
 };
 
+/* This lock is needed to prevent the situation where multiple encoders are
+ * initialised at the same time which appears to cause excessive CPU usage over
+ * some period of time. */
+G_LOCK_DEFINE_STATIC (initialization_lock);
+
 #if HAVE_NVENC_GST_GL
 struct gl_input_resource
 {
@@ -878,10 +883,14 @@ gst_nv_base_enc_set_format (GstVideoEncoder * enc, GstVideoCodecState * state)
   NVENCSTATUS nv_ret;
 
   g_assert (nvenc_class->initialize_encoder);
+
+  G_LOCK (initialization_lock);
   if (!nvenc_class->initialize_encoder (nvenc, old_state, state)) {
     GST_ERROR_OBJECT (enc, "Subclass failed to reconfigure encoder");
+    G_UNLOCK (initialization_lock);
     return FALSE;
   }
+  G_UNLOCK (initialization_lock);
 
   if (!nvenc->max_encode_width && !nvenc->max_encode_height) {
     gst_nv_base_enc_set_max_encode_size (nvenc, GST_VIDEO_INFO_WIDTH (info),
@@ -1020,7 +1029,10 @@ gst_nv_base_enc_set_format (GstVideoEncoder * enc, GstVideoCodecState * state)
       cout_buf.size = 1024 * 1024;
       cout_buf.memoryHeap = NV_ENC_MEMORY_HEAP_SYSMEM_CACHED;
 
+      G_LOCK (initialization_lock);
       nv_ret = NvEncCreateBitstreamBuffer (nvenc->encoder, &cout_buf);
+      G_UNLOCK (initialization_lock);
+
       if (nv_ret != NV_ENC_SUCCESS) {
         GST_WARNING_OBJECT (enc, "Failed to allocate input buffer: %d", nv_ret);
         /* FIXME: clean up */