Mesa (main): util,gallium: put count in pipe_resource & sampler_view on its own cache line
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Wed Oct 13 03:56:22 UTC 2021
Module: Mesa
Branch: main
Commit: 8c6e18bc513b98d92673163bced7631d8ee6eafc
URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=8c6e18bc513b98d92673163bced7631d8ee6eafc
Author: Marek Olšák <marek.olsak at amd.com>
Date: Sun Jun 27 17:55:29 2021 -0400
util,gallium: put count in pipe_resource & sampler_view on its own cache line
This adds 60 bytes to both structures. It eliminates "False Sharing"
for atomic operations (see wikipedia).
Reviewed-By: Mike Blumenkrantz <michael.blumenkrantz at gmail.com>
Reviewed-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer at amd.com>
Reviewed-by: Kristian H. Kristensen <hoegsberg at google.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/11618>
---
src/gallium/auxiliary/util/u_tests.c | 4 ++--
src/gallium/drivers/d3d12/d3d12_blit.cpp | 2 +-
src/gallium/drivers/d3d12/d3d12_surface.cpp | 2 +-
src/gallium/drivers/r300/r300_context.c | 4 ++--
src/gallium/include/pipe/p_compiler.h | 17 +++++++++++++++++
src/gallium/include/pipe/p_state.h | 7 +++++--
src/util/macros.h | 3 +++
src/util/u_memory.h | 4 ++++
8 files changed, 35 insertions(+), 8 deletions(-)
diff --git a/src/gallium/auxiliary/util/u_tests.c b/src/gallium/auxiliary/util/u_tests.c
index 6a67f63e219..71e954ff94d 100644
--- a/src/gallium/auxiliary/util/u_tests.c
+++ b/src/gallium/auxiliary/util/u_tests.c
@@ -48,7 +48,7 @@ util_create_texture2d(struct pipe_screen *screen, unsigned width,
unsigned height, enum pipe_format format,
unsigned num_samples)
{
- struct pipe_resource templ = {{0}};
+ struct pipe_resource templ = {0};
templ.target = PIPE_TEXTURE_2D;
templ.width0 = width;
@@ -698,7 +698,7 @@ test_texture_barrier(struct pipe_context *ctx, bool use_fbfetch,
"ADD OUT[0], TEMP[0], IMM[0]\n"
"END\n";
} else {
- struct pipe_sampler_view templ = {{0}};
+ struct pipe_sampler_view templ = {0};
templ.format = cb->format;
templ.target = cb->target;
templ.swizzle_r = PIPE_SWIZZLE_X;
diff --git a/src/gallium/drivers/d3d12/d3d12_blit.cpp b/src/gallium/drivers/d3d12/d3d12_blit.cpp
index d19c07c94d7..ed44263c8f8 100644
--- a/src/gallium/drivers/d3d12/d3d12_blit.cpp
+++ b/src/gallium/drivers/d3d12/d3d12_blit.cpp
@@ -469,7 +469,7 @@ create_staging_resource(struct d3d12_context *ctx,
unsigned mask)
{
- struct pipe_resource templ = {{0}};
+ struct pipe_resource templ = {};
struct pipe_resource *staging_res;
struct pipe_box copy_src;
diff --git a/src/gallium/drivers/d3d12/d3d12_surface.cpp b/src/gallium/drivers/d3d12/d3d12_surface.cpp
index 58516f6a343..610c87631f2 100644
--- a/src/gallium/drivers/d3d12/d3d12_surface.cpp
+++ b/src/gallium/drivers/d3d12/d3d12_surface.cpp
@@ -320,7 +320,7 @@ d3d12_surface_update_pre_draw(struct d3d12_surface *surface,
if (mode == D3D12_SURFACE_CONVERSION_BGRA_UINT) {
if (!surface->rgba_texture) {
- struct pipe_resource templ = {{0}};
+ struct pipe_resource templ = {};
struct pipe_resource *src = surface->base.texture;
templ.format = PIPE_FORMAT_R8G8B8A8_UNORM;
diff --git a/src/gallium/drivers/r300/r300_context.c b/src/gallium/drivers/r300/r300_context.c
index db5ad901f71..b5a7d10a075 100644
--- a/src/gallium/drivers/r300/r300_context.c
+++ b/src/gallium/drivers/r300/r300_context.c
@@ -441,8 +441,8 @@ struct pipe_context* r300_create_context(struct pipe_screen* screen,
* dummy texture there. */
if (!r300->screen->caps.is_r500) {
struct pipe_resource *tex;
- struct pipe_resource rtempl = {{0}};
- struct pipe_sampler_view vtempl = {{0}};
+ struct pipe_resource rtempl = {0};
+ struct pipe_sampler_view vtempl = {0};
rtempl.target = PIPE_TEXTURE_2D;
rtempl.format = PIPE_FORMAT_I8_UNORM;
diff --git a/src/gallium/include/pipe/p_compiler.h b/src/gallium/include/pipe/p_compiler.h
index 8c3a793e336..868cb09b023 100644
--- a/src/gallium/include/pipe/p_compiler.h
+++ b/src/gallium/include/pipe/p_compiler.h
@@ -155,6 +155,23 @@ typedef unsigned char boolean;
#endif
+/**
+ * Declare a variable on its own cache line.
+ *
+ * This helps eliminate "False sharing" to make atomic operations
+ * on pipe_reference::count faster and/or access to adjacent fields faster.
+ *
+ * https://en.wikipedia.org/wiki/False_sharing
+ *
+ * CALLOC_STRUCT_CL or MALLOC_STRUCT_CL and FREE_CL should be used to allocate
+ * structures that contain this.
+ *
+ * NOTE: Don't use PIPE_ALIGN_VAR because it causes the whole structure to be
+ * aligned, but we only want to align the field.
+ */
+#define EXCLUSIVE_CACHELINE(decl) \
+ union { char __cl_space[CACHE_LINE_SIZE]; \
+ decl; }
#if defined(__GNUC__)
diff --git a/src/gallium/include/pipe/p_state.h b/src/gallium/include/pipe/p_state.h
index a09abcc4e98..884d837dba3 100644
--- a/src/gallium/include/pipe/p_state.h
+++ b/src/gallium/include/pipe/p_state.h
@@ -472,7 +472,9 @@ struct pipe_surface
*/
struct pipe_sampler_view
{
- struct pipe_reference reference;
+ /* Put the refcount on its own cache line to prevent "False sharing". */
+ EXCLUSIVE_CACHELINE(struct pipe_reference reference);
+
enum pipe_format format:15; /**< typed PIPE_FORMAT_x */
enum pipe_texture_target target:5; /**< PIPE_TEXTURE_x */
unsigned swizzle_r:3; /**< PIPE_SWIZZLE_x for red component */
@@ -543,7 +545,8 @@ struct pipe_box
*/
struct pipe_resource
{
- struct pipe_reference reference;
+ /* Put the refcount on its own cache line to prevent "False sharing". */
+ EXCLUSIVE_CACHELINE(struct pipe_reference reference);
unsigned width0; /**< Used by both buffers and textures. */
uint16_t height0; /* Textures: The maximum height/depth/array_size is 16k. */
diff --git a/src/util/macros.h b/src/util/macros.h
index e179479fa20..35ffa80de5f 100644
--- a/src/util/macros.h
+++ b/src/util/macros.h
@@ -477,4 +477,7 @@ typedef int lock_cap_t;
#endif
+/* TODO: this could be different on non-x86 architectures. */
+#define CACHE_LINE_SIZE 64
+
#endif /* UTIL_MACROS_H */
diff --git a/src/util/u_memory.h b/src/util/u_memory.h
index 4cdccb66aaf..621f70c57df 100644
--- a/src/util/u_memory.h
+++ b/src/util/u_memory.h
@@ -90,6 +90,10 @@ mem_dup(const void *src, size_t size)
#define Offset(TYPE, MEMBER) ((uintptr_t)&(((TYPE *)NULL)->MEMBER))
+/* Allocate a structure aligned to a cache line. (used to make atomic ops faster) */
+#define MALLOC_STRUCT_CL(T) (struct T *)align_malloc(sizeof(struct T), CACHE_LINE_SIZE)
+#define CALLOC_STRUCT_CL(T) (struct T *)align_calloc(sizeof(struct T), CACHE_LINE_SIZE)
+#define FREE_CL(ptr) align_free(ptr)
#ifdef __cplusplus
}
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