diff options
Diffstat (limited to 'progs/demos/texdown.c')
| -rw-r--r-- | progs/demos/texdown.c | 133 |
1 files changed, 106 insertions, 27 deletions
diff --git a/progs/demos/texdown.c b/progs/demos/texdown.c index 79525a0395..fc98fddb31 100644 --- a/progs/demos/texdown.c +++ b/progs/demos/texdown.c @@ -38,8 +38,8 @@ #include <GL/glut.h> -static GLsizei MaxSize = 1024; -static GLsizei TexWidth = 256, TexHeight = 256, TexBorder = 0; +static GLsizei MaxSize = 2048; +static GLsizei TexWidth = 1024, TexHeight = 1024, TexBorder = 0; static GLboolean ScaleAndBias = GL_FALSE; static GLboolean SubImage = GL_FALSE; static GLdouble DownloadRate = 0.0; /* texels/sec */ @@ -47,6 +47,32 @@ static GLdouble DownloadRate = 0.0; /* texels/sec */ static GLuint Mode = 0; +/* Try and avoid L2 cache effects by cycling through a small number of + * textures. + * + * At the initial size of 1024x1024x4 == 4mbyte, say 8 textures will + * keep us out of most caches at 32mb total. + * + * This turns into a fairly interesting question of what exactly you + * expect to be in cache in normal usage, and what you think should be + * outside. There's no rules for this, no reason to favour one usage + * over another except what the application you care about happens to + * resemble most closely. + * + * - Should the client texture image be in L2 cache? Has it just been + * generated or read from disk? + * - Does the application really use >1 texture, or is it constantly + * updating one image in-place? + * + * Different answers will favour different texture upload mechanisms. + * To upload an image that is purely outside of cache, a DMA-based + * upload will probably win, whereas for small, in-cache textures, + * copying looks good. + */ +#define NR_TEXOBJ 4 +static GLuint TexObj[NR_TEXOBJ]; + + struct FormatRec { GLenum Format; GLenum Type; @@ -116,25 +142,57 @@ TypeStr(GLenum type) } } +/* On x86, there is a performance cliff for memcpy to texture memory + * for sources below 64 byte alignment. We do our best with this in + * the driver, but it is better if the images are correctly aligned to + * start with: + */ +#define ALIGN (1<<12) + +static unsigned align(unsigned value, unsigned a) +{ + return (value + a - 1) & ~(a-1); +} + +static int MIN2(int a, int b) +{ + return a < b ? a : b; +} static void MeasureDownloadRate(void) { const int w = TexWidth + 2 * TexBorder; const int h = TexHeight + 2 * TexBorder; - const int bytes = w * h * BytesPerTexel(Format); + const int image_bytes = align(w * h * BytesPerTexel(Format), ALIGN); + const int bytes = image_bytes * NR_TEXOBJ; + GLubyte *orig_texImage, *orig_getImage; GLubyte *texImage, *getImage; GLdouble t0, t1, time; int count; int i; + int offset = 0; + GLdouble total = 0; /* ints will tend to overflow */ + + printf("allocating %d bytes for %d %dx%d images\n", + bytes, NR_TEXOBJ, w, h); - texImage = (GLubyte *) malloc(bytes); - getImage = (GLubyte *) malloc(bytes); - if (!texImage || !getImage) { + orig_texImage = (GLubyte *) malloc(bytes + ALIGN); + orig_getImage = (GLubyte *) malloc(image_bytes + ALIGN); + if (!orig_texImage || !orig_getImage) { DownloadRate = 0.0; return; } + printf("alloc %p %p\n", orig_texImage, orig_getImage); + + texImage = (GLubyte *)align((unsigned)orig_texImage, ALIGN); + getImage = (GLubyte *)align((unsigned)orig_getImage, ALIGN); + + for (i = 1; !(((unsigned)texImage) & i); i<<=1) + ; + printf("texture image alignment: %d bytes (%p)\n", i, texImage); + for (i = 0; i < bytes; i++) { texImage[i] = i & 0xff; } @@ -166,16 +224,50 @@ MeasureDownloadRate(void) count = 0; t0 = glutGet(GLUT_ELAPSED_TIME) * 0.001; do { + int img = count%NR_TEXOBJ; + GLubyte *img_ptr = texImage + img * image_bytes; + + glBindTexture(GL_TEXTURE_2D, TexObj[img]); + if (SubImage && count > 0) { - glTexSubImage2D(GL_TEXTURE_2D, 0, -TexBorder, -TexBorder, w, h, + /* Only update a portion of the image each iteration. This + * is presumably why you'd want to use texsubimage, otherwise + * you may as well just call teximage again. + * + * A bigger question is whether to use a pointer that moves + * with each call, ie does the incoming data come from L2 + * cache under normal circumstances, or is it pulled from + * uncached memory? + * + * There's a good argument to say L2 cache, ie you'd expect + * the data to have been recently generated. It's possible + * that it could have come from a file read, which may or may + * not have gone through the cpu. + */ + glTexSubImage2D(GL_TEXTURE_2D, 0, + -TexBorder, + -TexBorder + offset * h/8, + w, + h/8, FormatTable[Format].Format, - FormatTable[Format].Type, texImage); + FormatTable[Format].Type, +#if 1 + texImage /* likely in L2$ */ +#else + img_ptr + offset * bytes/8 /* unlikely in L2$ */ +#endif + ); + offset += 1; + offset %= 8; + total += w * h / 8; } else { glTexImage2D(GL_TEXTURE_2D, 0, FormatTable[Format].IntFormat, w, h, TexBorder, FormatTable[Format].Format, - FormatTable[Format].Type, texImage); + FormatTable[Format].Type, + img_ptr); + total += w*h; } /* draw a tiny polygon to force texture into texram */ @@ -192,25 +284,12 @@ MeasureDownloadRate(void) glDisable(GL_TEXTURE_2D); - printf("w*h=%d count=%d time=%f\n", w*h, count, time); - DownloadRate = w * h * count / time; - -#if 0 - if (!ScaleAndBias) { - /* verify texture readback */ - glGetTexImage(GL_TEXTURE_2D, 0, - FormatTable[Format].Format, - FormatTable[Format].Type, getImage); - for (i = 0; i < w * h; i++) { - if (texImage[i] != getImage[i]) { - printf("[%d] %d != %d\n", i, texImage[i], getImage[i]); - } - } - } -#endif + printf("total texels=%f time=%f\n", total, time); + DownloadRate = total / time; + - free(texImage); - free(getImage); + free(orig_texImage); + free(orig_getImage); { GLint err = glGetError(); |