On 09/11/2012 10:40 PM, Daniel Vetter wrote:
> Only quick read-through but I'd have expected a has_llc check in there
> - if vlv is anything like the previous platforms wc gtt will be much
> faster there.
I'm not too familiar with why one would want to check has_llc here. I see that
has_llc is checked in only one place in i965, in a function that also writes to
a drm_intel_bo_map'd bo.
Are you suggesting that I replace the check for `intel->gen >= 6` with
`intel->has_llc`?
> On Tue, Sep 11, 2012 at 9:04 PM, Chad Versace
> <chad.vers...@linux.intel.com> wrote:
>> 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 | 10 184.6 187.4 15.9
>> after | 10 564.2 558.8 24.8
>>
>> Difference at 95.0% confidence:
>> 371.373 +/- 19.533
>> 198.192% +/- 10.4243%
>>
>> Ratio:
>> avg: 3.06
>> median: 2.99
>>
>> CC: Stéphane Marchesin <marc...@chromium.org>
>> Signed-off-by: Chad Versace <chad.vers...@linux.intel.com>
>> ---
>>
>> Stephane,
>>
>> This patch applies cleanly to master. Since the patch now occurs at
>> a significantly different point in history compared to the other patch I sent
>> you, I reran the workloads and updated the scores.
>>
>>
>> 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 | 170
>> ++++++++++++++++++++++++
>> 3 files changed, 193 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..d932f6e 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 +149,165 @@ 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 throuh 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. This expectation has been 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;
>> +
>> + /* Restrict to gen >= 6 because the performance impact on earlier
>> chipsets
>> + * has not been investigated.
>> + *
>> + * This function could be expanded to accommodate more textures and
>> + * chipets, but more performance inverstigation is needed.
>> + */
>> + if (intel->gen < 6 ||
>> + 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 +318,16 @@ 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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