[PATCH 0/2] MR5923: winegstreamer: Use affinity to determine 'max-threads' value.

[Brendan McGrath (＠redmcg)]

GStreamer uses _SC_NPROCESSORS_CONF to determine 'max-threads'. On the
Steam Deck, this is configured to be 16 (which is double its number
of logical cores).

_SC_NPROCESSORS_CONF also disregards a process's CPU affinity, thus it
can create more threads than is useful, which ultimately wastes memory
resources.

Using affinity to set 'max-threads' addresses both these problems.

[PATCH 1/2] winegstreamer: Use affinity to determine 'max-threads' value.

[Brendan McGrath]

From: Brendan McGrath

GStreamer uses _SC_NPROCESSORS_CONF to determine 'max-threads'. On the
Steam Deck, this is configured to be 16 (which is double its number
of logical cores).

_SC_NPROCESSORS_CONF also disregards a process's CPU affinity, thus it
can create more threads than is useful, which ultimately wastes memory
resources.

Using affinity to set 'max-threads' addresses both these problems.
---
 dlls/winegstreamer/wg_parser.c | 35 ++++++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/dlls/winegstreamer/wg_parser.c b/dlls/winegstreamer/wg_parser.c
index 7253013b6a3..dc820df2d24 100644
--- a/dlls/winegstreamer/wg_parser.c
+++ b/dlls/winegstreamer/wg_parser.c
@@ -567,6 +567,40 @@ static void no_more_pads_cb(GstElement *element, gpointer user)
     pthread_cond_signal(&parser->init_cond);
 }

+static void deep_element_added_cb(GstBin *self, GstBin *sub_bin, GstElement *element, gpointer user)
+{
+    GstElementFactory *factory = NULL;
+    const char *name = NULL;
+
+    if (element)
+        factory = gst_element_get_factory(element);
+
+    if (factory)
+        name = gst_element_factory_get_longname(factory);
+
+    if (name && strstr(name, "libav H.264"))
+    {
+        const gint32 MAX_THREADS = 16;
+        gint32 max_threads;
+
+#ifdef HAVE_SCHED_SETAFFINITY
+        gint32 thread_count;
+        cpu_set_t p_aff;
+        memset( &p_aff, 0, sizeof(p_aff) );
+        if( sched_getaffinity( 0, sizeof(p_aff), &p_aff ) )
+            thread_count = 0;
+        else
+            thread_count = CPU_COUNT(&p_aff);
+#else
+        /* A thread_count of 0 is the default value for gstreamer and means 'auto' */
+        gint32 thread_count = 0;
+#endif
+        max_threads = MIN(thread_count, MAX_THREADS);
+        GST_DEBUG("%s found, setting max-threads to %d.", name, max_threads);
+        g_object_set(element, "max-threads", max_threads, NULL);
+    }
+}
+
 static gboolean sink_event_cb(GstPad *pad, GstObject *parent, GstEvent *event)
 {
     struct wg_parser_stream *stream = gst_pad_get_element_private(pad);
@@ -1797,6 +1831,7 @@ static BOOL decodebin_parser_init_gst(struct wg_parser *parser)
     g_signal_connect(element, "autoplug-continue", G_CALLBACK(autoplug_continue_cb), parser);
     g_signal_connect(element, "autoplug-select", G_CALLBACK(autoplug_select_cb), parser);
     g_signal_connect(element, "no-more-pads", G_CALLBACK(no_more_pads_cb), parser);
+    g_signal_connect(element, "deep-element-added", G_CALLBACK(deep_element_added_cb), parser);

pthread_mutex_lock(&parser->mutex);
     parser->no_more_pads = false;

[PATCH 2/2] winegstreamer: Set MAX_THREADS to 4 for i386.

[Brendan McGrath]

From: Brendan McGrath

The avdec_h264 element can use 32MB per thread when working with 4K video.

With 16 threads, this is 512MB, which is a quarter of the RAM available
to a 32-bit application. Setting MAX_THREADS to 4 can save 384MB.
---
 dlls/winegstreamer/wg_parser.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/dlls/winegstreamer/wg_parser.c b/dlls/winegstreamer/wg_parser.c
index dc820df2d24..a058ab08715 100644
--- a/dlls/winegstreamer/wg_parser.c
+++ b/dlls/winegstreamer/wg_parser.c
@@ -580,7 +580,11 @@ static void deep_element_added_cb(GstBin *self, GstBin *sub_bin, GstElement *ele

if (name && strstr(name, "libav H.264"))
     {
+#if defined(__i386__)
+        const gint32 MAX_THREADS = 4;
+#else
         const gint32 MAX_THREADS = 16;
+#endif
         gint32 max_threads;

#ifdef HAVE_SCHED_SETAFFINITY

[Rémi Bernon (＠rbernon)]

Rémi Bernon (@rbernon) commented about dlls/winegstreamer/wg_parser.c:
> - if (factory)
> -
>    name = gst_element_factory_get_longname(factory);
> -
> - if (name && strstr(name, "libav H.264"))
> - {
> -
>    const gint32 MAX_THREADS = 16;
> -
>    gint32 max_threads;
> -
>
> +#ifdef HAVE_SCHED_SETAFFINITY
> -
>    gint32 thread_count;
> -
>    cpu_set_t p_aff;
> -
>    memset( &p_aff, 0, sizeof(p_aff) );
> -
>    if( sched_getaffinity( 0, sizeof(p_aff), &p_aff ) )
> -
>        thread_count = 0;
> -
>    else
> -
>        thread_count = CPU_COUNT(&p_aff);

What about using Nt functions instead? NtQueryInformationThread( ThreadBasicInformation ), and counting the bits in `info.AffinityMask`?

It could probably better be done in `wg_init_gstreamer`, as this callback may be called in a non-wine thread.

[Rémi Bernon (＠rbernon)]

Rémi Bernon (@rbernon) commented about dlls/winegstreamer/wg_parser.c:
>  pthread_cond_signal(&parser->init_cond);
>
> }
>
> +static void deep_element_added_cb(GstBin *self, GstBin *sub_bin, GstElement *element, gpointer user)
> +{
> - GstElementFactory *factory = NULL;
> - const char *name = NULL;
> -
> - if (element)
> -
>    factory = gst_element_get_factory(element);
> -
> - if (factory)
> -
>    name = gst_element_factory_get_longname(factory);
> -
> - if (name && strstr(name, "libav H.264"))

Do we need to check the name? Could we just set the property unconditionally? If we need to check the name I would rather check that the element short name starts with `avdec_`, as is the case for every libav decoder.

[Rémi Bernon (＠rbernon)]

Note that this will not change the behavior of the standalone H264 decoder, you will need to do a similar thing in `wg_transform`.