st/mesa: regularly re-pin driver threads to the CCX where the app thread is

This is used when glthread is disabled.

Mesa pretty much chases the app thread on the CPU.
The performance is the same as pinning the app thread.

Reviewed-by: Dave Airlie <airlied@redhat.com>

diff --git a/src/mesa/state_tracker/st_context.h b/src/mesa/state_tracker/st_context.h
index 14b9b018809f8821394a6288164504a776b7917f..95133c7020f35d777bb30a84e2cd692509ba5763 100644 (file)
--- a/src/mesa/state_tracker/st_context.h
+++ b/src/mesa/state_tracker/st_context.h
@@ -193,6 +193,8 @@ struct st_context
    /** This masks out unused shader resources. Only valid in draw calls. */
    uint64_t active_states;
 
+   unsigned pin_thread_counter; /* for L3 thread pinning on AMD Zen */
+
    /* If true, further analysis of states is required to know if something
     * has changed. Used mainly for shaders.
     */

diff --git a/src/mesa/state_tracker/st_draw.c b/src/mesa/state_tracker/st_draw.c
index eb52d9505b68fc58910478608f0256151cc11a8c..5910ffa5bdaeb92e48e36e2ab8d6812c91f1a0ec 100644 (file)
--- a/src/mesa/state_tracker/st_draw.c
+++ b/src/mesa/state_tracker/st_draw.c
@@ -58,6 +58,7 @@
 
 #include "pipe/p_context.h"
 #include "pipe/p_defines.h"
+#include "util/u_cpu_detect.h"
 #include "util/u_inlines.h"
 #include "util/u_format.h"
 #include "util/u_prim.h"
@@ -66,6 +67,13 @@
 #include "draw/draw_context.h"
 #include "cso_cache/cso_context.h"
 
+#ifdef PIPE_OS_LINUX
+#include <sched.h>
+#define HAVE_SCHED_GETCPU 1
+#else
+#define sched_getcpu() 0
+#define HAVE_SCHED_GETCPU 0
+#endif
 
 /**
  * Set the restart index.
@@ -122,6 +130,30 @@ prepare_draw(struct st_context *st, struct gl_context *ctx)
        st->gfx_shaders_may_be_dirty) {
       st_validate_state(st, ST_PIPELINE_RENDER);
    }
+
+   struct pipe_context *pipe = st->pipe;
+
+   /* Pin threads regularly to the same Zen CCX that the main thread is
+    * running on. The main thread can move between CCXs.
+    */
+   if (unlikely(HAVE_SCHED_GETCPU && /* Linux */
+                /* AMD Zen */
+                util_cpu_caps.nr_cpus != util_cpu_caps.cores_per_L3 &&
+                /* no glthread */
+                ctx->CurrentClientDispatch != ctx->MarshalExec &&
+                /* driver support */
+                pipe->set_context_param &&
+                /* do it occasionally */
+                ++st->pin_thread_counter % 512 == 0)) {
+      int cpu = sched_getcpu();
+      if (cpu >= 0) {
+         unsigned L3_cache = cpu / util_cpu_caps.cores_per_L3;
+
+         pipe->set_context_param(pipe,
+                                 PIPE_CONTEXT_PARAM_PIN_THREADS_TO_L3_CACHE,
+                                 L3_cache);
+      }
+   }
 }
 
 /**