[Mesa-dev] [PATCH] intel: Improve teximage perf for Google Chrome paint rects (v3)
Chad Versace
chad.versace at linux.intel.com
Thu Sep 20 12:55:09 PDT 2012
This patch reduces the time spent in glTexImage and glTexSubImage by
over 5x on Sandybridge for the workload described below.
It 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 for chipsets with a LLC.
=== 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 21.0.1180.89 (154005)
Statistics:
| N Median Avg Stddev
--------------|-------------------------
before (msec) | 8 472.5 463.75 72.6
after (msec) | 8 78.0 79.6 5.7
Arithmetic difference at 95.0% confidence:
-384.1 +/- 55.2 msec
-82.8% +/- 11.9%
Ratio at 95.0% confidence:
5.81 +/- 0.119
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.
v3:
- If the current batch references the bo, then flush batch before mapping
the bo. Found by Chris.
- Restrict supported texture images to level 0 of target
GL_TEXTURE_2D. This avoids an arithmetic bug in calculating image
offsets within the miptree, found by Paul. This restriction does not
diminish this patch's benefit to Chrome OS performance.
- Use less instructions for bit6 swizzling, suggested by Paul.
- Remove erroneous comment about Y-tiling, for Paul.
- Print perf_debug messages when flushing and stalling.
- Update stats in commit message; run workload under a release build
rather than a debug build.
Note: This is a candidate for the 9.0 branch.
CC: Paul Berry <stereotype441 at gmail.com>
CC: Chris Wilson <chris at chris-wilson.co.uk>
CC: Stéphane Marchesin <marcheu at chromium.org>
Signed-off-by: Chad Versace <chad.versace at 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 | 163 ++++++++++++++++++++++++
3 files changed, 186 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..d3a8736 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"
@@ -33,6 +34,7 @@
#include "main/texcompress.h"
#include "main/enums.h"
+#include "intel_batchbuffer.h"
#include "intel_context.h"
#include "intel_tex.h"
#include "intel_mipmap_tree.h"
@@ -148,6 +150,157 @@ 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.
+ *
+ * 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. On some workloads, the
+ * performance gain of this fastpath on Sandybridge is over 5x.
+ */
+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);
+
+ /* The miptree's buffer. */
+ drm_intel_bo *bo;
+
+ int error = 0;
+
+ /* This fastpath is restricted to a specific texture type: level 0 of
+ * a 2D BGRA texture. It could be generalized to support more types by
+ * varying the arithmetic loop below.
+ */
+ if (!intel->has_llc ||
+ format != GL_BGRA ||
+ type != GL_UNSIGNED_BYTE ||
+ texImage->TexObject->Target != GL_TEXTURE_2D ||
+ texImage->Level != 0 ||
+ 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. */
+ return false;
+ }
+
+ bo = image->mt->region->bo;
+
+ if (drm_intel_bo_references(intel->batch.bo, bo)) {
+ perf_debug("Flushing before mapping a referenced bo.\n");
+ intel_batchbuffer_flush(intel);
+ }
+
+ if (unlikely(INTEL_DEBUG & DEBUG_PERF)) {
+ if (drm_intel_bo_busy(bo)) {
+ perf_debug("Mapping a busy BO, causing a stall on the GPU.\n");
+ }
+ }
+
+ error = drm_intel_bo_map(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 suffixed with its units.
+ */
+
+ const uint32_t x_max_pixels = xoffset + width;
+ const uint32_t y_max_pixels = 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;
+
+ for (uint32_t y_pixels = yoffset; y_pixels < y_max_pixels; ++y_pixels) {
+ const uint32_t y_offset_bytes = (y_pixels / tile_height) * width_tiles * tile_size_bytes
+ + (y_pixels % tile_height) * tile_width_bytes;
+
+ for (uint32_t x_pixels = xoffset; x_pixels < x_max_pixels; x_pixels += swizzle_width_pixels) {
+ const uint32_t x_offset_bytes = (x_pixels / tile_width_pixels) * tile_size_bytes
+ + (x_pixels % tile_width_pixels) * cpp;
+
+ intptr_t offset_bytes = y_offset_bytes + x_offset_bytes;
+ if (intel->has_swizzling) {
+#if 0
+ /* Clear, unoptimized version. */
+ bool bit6 = (offset_bytes >> 6) & 1;
+ bool bit9 = (offset_bytes >> 9) & 1;
+ bool bit10 = (offset_bytes >> 10) & 1;
+
+ if (bit9 ^ bit10)
+ offset_bytes ^= (1 << 6);
+#else
+ /* Optimized, obfuscated version. */
+ offset_bytes ^= ((offset_bytes >> 3) ^ (offset_bytes >> 4))
+ & (1 << 6);
+#endif
+ }
+
+ const uint32_t swizzle_bound_pixels = ALIGN(x_pixels + 1, swizzle_width_pixels);
+ const uint32_t memcpy_bound_pixels = MIN2(x_max_pixels, swizzle_bound_pixels);
+ const uint32_t copy_size = cpp * (memcpy_bound_pixels - x_pixels);
+
+ memcpy(bo->virtual + offset_bytes, pixels, copy_size);
+ pixels += copy_size;
+ x_pixels -= (x_pixels % swizzle_width_pixels);
+ }
+ }
+
+ drm_intel_bo_unmap(bo);
+ return true;
+}
+
static void
intelTexSubImage(struct gl_context * ctx,
GLuint dims,
@@ -158,6 +311,16 @@ 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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