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authorKeith Whitwell <keithw@vmware.com>2009-07-29 12:47:23 +0100
committerKeith Whitwell <keithw@vmware.com>2009-07-29 12:48:05 +0100
commit684282953937a37541f26c6e51ceec4134c62dfb (patch)
treedda349470ecde577bf5ecdb7ab4f8c38019717e0 /src/mesa
parent2420b283b783751d4def3a3a2a0ed8bf7bb7b6a8 (diff)
mesa/st: short-circuit glFinish calls on WIN32 only
Windows opengl32.dll calls glFinish prior to every swapbuffers, which makes it pretty hard to get decent performance... Work around by mapping finish to flush on PIPE_OS_WINDOWS. This is conformant, though it might confuse poorly-written benchmarks which attempt to measure a single event rather than figuring out the rate of continuous processing.
Diffstat (limited to 'src/mesa')
-rw-r--r--src/mesa/state_tracker/st_cb_flush.c12
1 files changed, 12 insertions, 0 deletions
diff --git a/src/mesa/state_tracker/st_cb_flush.c b/src/mesa/state_tracker/st_cb_flush.c
index fbaffd154f..f7de4e7a4d 100644
--- a/src/mesa/state_tracker/st_cb_flush.c
+++ b/src/mesa/state_tracker/st_cb_flush.c
@@ -152,4 +152,16 @@ void st_init_flush_functions(struct dd_function_table *functions)
{
functions->Flush = st_glFlush;
functions->Finish = st_glFinish;
+
+ /* Windows opengl32.dll calls glFinish prior to every swapbuffers.
+ * This is unnecessary and degrades performance. Luckily we have some
+ * scope to work around this, as the externally-visible behaviour of
+ * Finish() is identical to Flush() in all cases - no differences in
+ * rendering or ReadPixels are visible if we opt not to wait here.
+ *
+ * Only set this up on windows to avoid suprise elsewhere.
+ */
+#ifdef PIPE_OS_WINDOWS
+ functions->Finish = st_glFlush;
+#endif
}