This patch adds a new fast path for glTexImage2D and glTexSubImage2D,
intel_texsubimage_tiled_memcpy, which is optimized for Google Chrome's
paint rectangles. The fast path is implemented only for 2D GL_BGRA
textures on gen >= 6.
Reduces the time spent in glTexImage and glTexSubImage by roughly 3x on
Sandybridge for the workload described below.
=== Performance Analysis ===
Workload description:
Personalize your google.com page with a wallpaper. Start chromium
with flags "--ignore-gpu-blacklist --enable-accelerated-painting
--force-compositing-mode". Start recording with chrome://tracing. Visit
google.com and wait for page to finish rendering. Measure the time spent
by process CrGpuMain in GLES2DecoderImpl::HandleTexImage2D and
HandleTexSubImage2D.
System config:
cpu: Sandybridge Mobile GT2+ (0x0126)
kernel 3.4.9 x86_64
chromium 21.0.1180.81 (151980)
Statistics:
| N Median Avg Stddev
-------|--------------------------
before | 10 564.2 558.8 24.8
after | 10 184.6 187.4 15.9
Difference at 95.0% confidence:
371.373 +/- 19.533
198.192% +/- 10.4243%
Ratio:
avg: 3.06
median: 2.99
v2:
- Replace check for `intel->gen >= 6` with `intel->has_llc`, per
danvet.
- Fix typo in comment, s/throuh/through/.
- Swap 'before' and 'after' rows in stat table.
CC: Stéphane Marchesin <marc...@chromium.org>
CC: Daniel Vetter <dan...@ffwll.ch>
Signed-off-by: Chad Versace <chad.vers...@linux.intel.com>
---
src/mesa/drivers/dri/intel/intel_tex.h | 11 ++
src/mesa/drivers/dri/intel/intel_tex_image.c | 12 ++
src/mesa/drivers/dri/intel/intel_tex_subimage.c | 168 ++++++++++++++++++++++++
3 files changed, 191 insertions(+)
diff --git a/src/mesa/drivers/dri/intel/intel_tex.h
b/src/mesa/drivers/dri/intel/intel_tex.h
index 88a7d55..777574d 100644
--- a/src/mesa/drivers/dri/intel/intel_tex.h
+++ b/src/mesa/drivers/dri/intel/intel_tex.h
@@ -85,4 +85,15 @@ bool intel_copy_texsubimage(struct intel_context *intel,
GLint x, GLint y,
GLsizei width, GLsizei height);
+bool
+intel_texsubimage_tiled_memcpy(struct gl_context *ctx,
+ GLuint dims,
+ struct gl_texture_image *texImage,
+ GLint xoffset, GLint yoffset, GLint zoffset,
+ GLsizei width, GLsizei height, GLsizei depth,
+ GLenum format, GLenum type,
+ const GLvoid *pixels,
+ const struct gl_pixelstore_attrib *packing,
+ bool for_glTexImage);
+
#endif
diff --git a/src/mesa/drivers/dri/intel/intel_tex_image.c
b/src/mesa/drivers/dri/intel/intel_tex_image.c
index fe9040c..bbb2fe0 100644
--- a/src/mesa/drivers/dri/intel/intel_tex_image.c
+++ b/src/mesa/drivers/dri/intel/intel_tex_image.c
@@ -206,10 +206,22 @@ intelTexImage(struct gl_context * ctx,
GLenum format, GLenum type, const void *pixels,
const struct gl_pixelstore_attrib *unpack)
{
+ bool ok;
+
DBG("%s target %s level %d %dx%dx%d\n", __FUNCTION__,
_mesa_lookup_enum_by_nr(texImage->TexObject->Target),
texImage->Level, texImage->Width, texImage->Height, texImage->Depth);
+ ok = intel_texsubimage_tiled_memcpy(ctx, dims, texImage,
+ 0, 0, 0, /*x,y,z offsets*/
+ texImage->Width,
+ texImage->Height,
+ texImage->Depth,
+ format, type, pixels, unpack,
+ true /*for_glTexImage*/);
+ if (ok)
+ return;
+
/* Attempt to use the blitter for PBO image uploads.
*/
if (dims <= 2 &&
diff --git a/src/mesa/drivers/dri/intel/intel_tex_subimage.c
b/src/mesa/drivers/dri/intel/intel_tex_subimage.c
index ae4b3bc..b030a65 100644
--- a/src/mesa/drivers/dri/intel/intel_tex_subimage.c
+++ b/src/mesa/drivers/dri/intel/intel_tex_subimage.c
@@ -26,6 +26,7 @@
*
**************************************************************************/
+#include "main/macros.h"
#include "main/mtypes.h"
#include "main/pbo.h"
#include "main/texobj.h"
@@ -148,6 +149,163 @@ intel_blit_texsubimage(struct gl_context * ctx,
return true;
}
+/**
+ * \brief A fast path for glTexImage and glTexSubImage.
+ *
+ * \param for_glTexImage Was this called from glTexImage or glTexSubImage?
+ *
+ * This fast path is taken when the hardware natively supports the texture
+ * format (such as GL_BGRA) and when the texture memory is X-tiled. It uploads
+ * the texture data by mapping the texture memory without a GTT fence, thus
+ * acquiring a tiled view of the memory, and then memcpy'ing sucessive
+ * subspans within each tile.
+ *
+ * This is a performance win over the conventional texture upload path because
+ * it avoids the performance penalty of writing through the write-combine
+ * buffer. In the conventional texture upload path,
+ * texstore.c:store_texsubimage(), the texture memory is mapped through a GTT
+ * fence, thus acquiring a linear view of the memory, then each row in the
+ * image is memcpy'd. In this fast path, we replace each row's memcpy with
+ * a sequence of memcpy's over each bit6 swizzle span in the row. A large
+ * memcpy through the write-combine buffer has been observed on Sandybridge to
+ * be approximately 3x slower than a memcpy to normal memory. So, one would
+ * expect this fast path to be approximately 3x faster than the conventional
+ * texture upload path, and that expectation is confirmed on Sandybridge for
+ * 256x256 GL_BGRA textures.
+ *
+ * This fast path's use case is Google Chrome's paint rectangles. Chrome (as
+ * of version 21) renders each page as a tiling of 256x256 GL_BGRA textures.
+ * Each page's content is initially uploaded with glTexImage2D and damaged
+ * regions are updated with glTexSubImage2D.
+ */
+bool
+intel_texsubimage_tiled_memcpy(struct gl_context * ctx,
+ GLuint dims,
+ struct gl_texture_image *texImage,
+ GLint xoffset, GLint yoffset, GLint zoffset,
+ GLsizei width, GLsizei height, GLsizei depth,
+ GLenum format, GLenum type,
+ const GLvoid *pixels,
+ const struct gl_pixelstore_attrib *packing,
+ bool for_glTexImage)
+{
+ struct intel_context *intel = intel_context(ctx);
+ struct intel_texture_image *image = intel_texture_image(texImage);
+
+ /* Offset into the miptree for the texture image. */
+ uint32_t image_offset_x;
+ uint32_t image_offset_y;
+
+ /* The miptree's buffer. */
+ drm_intel_bo *bo;
+
+ int error = 0;
+
+ /* This fastpath is restricted to a specific texture type: 2D GL_BGRA.
+ * It could be generalized to support more types by varying the arithmetic
+ * loop below.
+ */
+ if (!intel->has_llc ||
+ dims != 2 ||
+ depth != 1 ||
+ format != GL_BGRA ||
+ type != GL_UNSIGNED_BYTE ||
+ pixels == NULL ||
+ packing->Alignment > 4)
+ return false;
+
+ if (for_glTexImage)
+ ctx->Driver.AllocTextureImageBuffer(ctx, texImage);
+
+ if (!image->mt ||
+ image->mt->region->tiling != I915_TILING_X) {
+ /* The algorithm below is written only for X-tiled memory.
+ *
+ * Memcpy'ing to Y-tiled memory is likely faster when done the
+ * conventional way: that is, map the memory through a fence in order to
+ * acquire a linear view of the memory, then memcpy one row at a time.
+ * Due to the arrangement of Y-tiled memory, if we were to upload
+ * a Y-tiled buffer using the algorithm below, then we could only copy
+ * one byte at a time.
+ */
+ return false;
+ }
+
+ intel_miptree_get_image_offset(image->mt,
+ texImage->Level,
+ texImage->Face,
+ 0 /*layer*/,
+ &image_offset_x,
+ &image_offset_y);
+
+ bo = image->mt->region->bo;
+ error = drm_intel_bo_map(image->mt->region->bo, true /*write_enable*/);
+ if (error || bo->virtual == NULL) {
+ DBG("%s: failed to map bo\n", __FUNCTION__);
+ return false;
+ }
+
+ /* We postponed printing this message until having committed to executing
+ * the function.
+ */
+ DBG("%s: level=%d offset=(%d,%d) (w,h)=(%d,%d)\n",
+ __FUNCTION__, texImage->Level, xoffset, yoffset, width, height);
+
+ /* In the tiling algorithm below, some variables are in units of pixels,
+ * others are in units of bytes, and others (such as height) are unitless.
+ * Each variable name is either prefixed or suffixed with its units.
+ */
+
+ const uint32_t pixel_max_x = xoffset + width;
+ const uint32_t pixel_max_y = yoffset + height;
+
+ const uint32_t tile_size_bytes = 4096;
+
+ const uint32_t tile_width_bytes = 512;
+ const uint32_t tile_width_pixels = 128;
+
+ const uint32_t tile_height = 8;
+
+ const uint32_t cpp = 4; /* chars per pixel of GL_BGRA */
+ const uint32_t swizzle_width_pixels = 16;
+
+ const uint32_t stride_bytes = image->mt->region->pitch * cpp;
+ const uint32_t width_tiles = stride_bytes / tile_width_bytes;
+
+ uint8_t *map = bo->virtual
+ + image_offset_y * stride_bytes
+ + image_offset_x * cpp;
+
+ for (uint32_t pixel_y = yoffset; pixel_y < pixel_max_y; ++pixel_y) {
+ const uint32_t byte_offset_y = (pixel_y / tile_height) * width_tiles *
tile_size_bytes
+ + (pixel_y % tile_height) *
tile_width_bytes;
+
+ for (uint32_t pixel_x = xoffset; pixel_x < pixel_max_x; pixel_x +=
swizzle_width_pixels) {
+ const uint32_t byte_offset_x = (pixel_x / tile_width_pixels) *
tile_size_bytes
+ + (pixel_x % tile_width_pixels) * cpp;
+ intptr_t byte_offset = byte_offset_y + byte_offset_x;
+ if (intel->has_swizzling) {
+ bool bit6 = (byte_offset >> 6) & 1;
+ bool bit9 = (byte_offset >> 9) & 1;
+ bool bit10 = (byte_offset >> 10) & 1;
+
+ byte_offset += 64 * (bit9 ^ bit10) * (1 - 2 * bit6);
+ }
+
+ const uint32_t swizzle_bound_pixels = ALIGN(pixel_x + 1,
swizzle_width_pixels);
+ const uint32_t memcpy_bound_pixels = MIN2(pixel_max_x,
swizzle_bound_pixels);
+ const uint32_t copy_size = cpp * (memcpy_bound_pixels - pixel_x);
+
+ memcpy(map + byte_offset, pixels, copy_size);
+ pixels += copy_size;
+ pixel_x -= (pixel_x % swizzle_width_pixels);
+ }
+ }
+
+ drm_intel_bo_unmap(bo);
+ return true;
+}
+
static void
intelTexSubImage(struct gl_context * ctx,
GLuint dims,
@@ -158,6 +316,16 @@ intelTexSubImage(struct gl_context * ctx,
const GLvoid * pixels,
const struct gl_pixelstore_attrib *packing)
{
+ bool ok;
+
+ ok = intel_texsubimage_tiled_memcpy(ctx, dims, texImage,
+ xoffset, yoffset, zoffset,
+ width, height, depth,
+ format, type, pixels, packing,
+ false /*for_glTexImage*/);
+ if (ok)
+ return;
+
/* The intel_blit_texsubimage() function only handles 2D images */
if (dims != 2 || !intel_blit_texsubimage(ctx, texImage,
xoffset, yoffset,
--
1.7.12
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