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i965/gen6: Improve glReadPixels() performance by blitting to a linear temp.

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The readpixels microbenchmark in mesa-demos goes from 47Mpix/sec at
1000x1000 to 450Mpix/sec.  The 10x10 sizes stay about the same.

Reviewed-by: Brian Paul <brianp@vmware.com>
This commit is contained in:
Eric Anholt 2011-10-19 10:31:40 -07:00
parent a1488eec38
commit eab201bad4
2 changed files with 81 additions and 8 deletions
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87
src/mesa/drivers/dri/intel/intel_fbo.c
View file

@ -42,6 +42,7 @@
#include "intel_context.h"
#include "intel_batchbuffer.h"
#include "intel_buffers.h"
#include "intel_blit.h"
#include "intel_fbo.h"
#include "intel_mipmap_tree.h"
#include "intel_regions.h"
@ -95,7 +96,7 @@ intel_map_renderbuffer(struct gl_context *ctx,
struct intel_context *intel = intel_context(ctx);
struct intel_renderbuffer *irb = intel_renderbuffer(rb);
GLubyte *map;
int stride;
int stride, flip_stride;
/* We sometimes get called with this by our intel_span.c usage. */
if (!irb->region) {
@ -145,24 +146,92 @@ intel_map_renderbuffer(struct gl_context *ctx,
x, y, w, h, *out_map, *out_stride);
return;
} else if (intel->gen >= 6 &&
!(mode & GL_MAP_WRITE_BIT) &&
irb->region->tiling == I915_TILING_X) {
int dst_stride = ALIGN(w * irb->region->cpp, 4);
int src_x, src_y;
/* On gen6+, we have LLC sharing, which means we can get high-performance
* access to linear-mapped buffers. So, blit out a tiled buffer (if
* possible, which it isn't really for Y tiling) to a temporary BO and
* return a map of that.
*/
if (rb->Name) {
src_x = x + irb->draw_x;
src_y = y + irb->draw_y;
} else {
src_x = x;
src_y = irb->region->height - y - h;
}
irb->map_bo = drm_intel_bo_alloc(intel->bufmgr, "MapRenderbuffer() temp",
dst_stride * h, 4096);
/* We don't do the flip in the blit, because it's always so tricky to get
* right.
*/
if (irb->map_bo &&
intelEmitCopyBlit(intel,
irb->region->cpp,
irb->region->pitch, irb->region->bo,
0, irb->region->tiling,
dst_stride / irb->region->cpp, irb->map_bo,
0, I915_TILING_NONE,
src_x, src_y,
0, 0,
w, h,
GL_COPY)) {
intel_batchbuffer_flush(intel);
drm_intel_bo_map(irb->map_bo, false);
if (rb->Name) {
*out_map = irb->map_bo->virtual;
*out_stride = dst_stride;
} else {
*out_map = irb->map_bo->virtual + (h - 1) * dst_stride;
*out_stride = -dst_stride;
}
DBG("%s: rb %d (%s) blit mapped: (%d, %d) (%dx%d) -> %p/%d\n",
__FUNCTION__, rb->Name, _mesa_get_format_name(rb->Format),
src_x, src_y, w, h, *out_map, *out_stride);
return;
} else {
drm_intel_bo_unreference(irb->map_bo);
irb->map_bo = NULL;
}
}
map = intel_region_map(intel, irb->region, mode);
stride = irb->region->pitch * irb->region->cpp;
if (rb->Name == 0) {
map += stride * (irb->region->height - 1);
stride = -stride;
y = irb->region->height - 1 - y;
flip_stride = -stride;
} else {
map += irb->draw_x * irb->region->cpp;
map += (int)irb->draw_y * stride;
x += irb->draw_x;
y += irb->draw_y;
flip_stride = stride;
}
if (drm_intel_bo_references(intel->batch.bo, irb->region->bo)) {
intel_batchbuffer_flush(intel);
}
drm_intel_gem_bo_map_gtt(irb->region->bo);
map = irb->region->bo->virtual;
map += x * irb->region->cpp;
map += (int)y * stride;
*out_map = map;
*out_stride = stride;
*out_stride = flip_stride;
DBG("%s: rb %d (%s) gtt mapped: (%d, %d) (%dx%d) -> %p/%d\n",
__FUNCTION__, rb->Name, _mesa_get_format_name(rb->Format),
x, y, w, h, *out_map, *out_stride);
}
static void
@ -202,6 +271,10 @@ intel_unmap_renderbuffer(struct gl_context *ctx,
intel_region_unmap(intel, irb->region);
free(irb->map_buffer);
irb->map_buffer = NULL;
} else if (irb->map_bo) {
drm_intel_bo_unmap(irb->map_bo);
drm_intel_bo_unreference(irb->map_bo);
irb->map_bo = 0;
} else {
if (irb->region)
intel_region_unmap(intel, irb->region);

2
src/mesa/drivers/dri/intel/intel_fbo.h
View file

@ -44,6 +44,7 @@ struct intel_renderbuffer
{
struct gl_renderbuffer Base;
struct intel_region *region;
drm_intel_bo *map_bo;
void *map_buffer;
GLuint map_x, map_y, map_w, map_h;
GLbitfield map_mode;
@ -60,7 +61,6 @@ struct intel_renderbuffer
*/
struct gl_renderbuffer *wrapped_depth;
struct gl_renderbuffer *wrapped_stencil;
/** \} */
GLuint draw_x, draw_y; /**< Offset of drawing within the region */