Optimize screendump
When running kvm-autotest, fputc() is often the second highest (sometimes #1) function showing up in a profile. This is due to fputc() locking the file for every byte written. Optimize by buffering a line's worth of pixels and writing that out in a single call. Reviewed-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com> Signed-off-by: Avi Kivity <avi@redhat.com> Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
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parent
9319a6d3a6
commit
f8e378f27f
13
hw/vga.c
13
hw/vga.c
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@ -2346,15 +2346,19 @@ int ppm_save(const char *filename, struct DisplaySurface *ds)
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uint32_t v;
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uint32_t v;
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int y, x;
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int y, x;
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uint8_t r, g, b;
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uint8_t r, g, b;
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int ret;
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char *linebuf, *pbuf;
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f = fopen(filename, "wb");
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f = fopen(filename, "wb");
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if (!f)
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if (!f)
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return -1;
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return -1;
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fprintf(f, "P6\n%d %d\n%d\n",
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fprintf(f, "P6\n%d %d\n%d\n",
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ds->width, ds->height, 255);
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ds->width, ds->height, 255);
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linebuf = qemu_malloc(ds->width * 3);
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d1 = ds->data;
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d1 = ds->data;
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for(y = 0; y < ds->height; y++) {
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for(y = 0; y < ds->height; y++) {
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d = d1;
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d = d1;
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pbuf = linebuf;
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for(x = 0; x < ds->width; x++) {
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for(x = 0; x < ds->width; x++) {
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if (ds->pf.bits_per_pixel == 32)
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if (ds->pf.bits_per_pixel == 32)
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v = *(uint32_t *)d;
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v = *(uint32_t *)d;
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@ -2366,13 +2370,16 @@ int ppm_save(const char *filename, struct DisplaySurface *ds)
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(ds->pf.gmax + 1);
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(ds->pf.gmax + 1);
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b = ((v >> ds->pf.bshift) & ds->pf.bmax) * 256 /
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b = ((v >> ds->pf.bshift) & ds->pf.bmax) * 256 /
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(ds->pf.bmax + 1);
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(ds->pf.bmax + 1);
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fputc(r, f);
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*pbuf++ = r;
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fputc(g, f);
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*pbuf++ = g;
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fputc(b, f);
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*pbuf++ = b;
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d += ds->pf.bytes_per_pixel;
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d += ds->pf.bytes_per_pixel;
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}
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}
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d1 += ds->linesize;
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d1 += ds->linesize;
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ret = fwrite(linebuf, 1, pbuf - linebuf, f);
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(void)ret;
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}
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}
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qemu_free(linebuf);
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fclose(f);
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fclose(f);
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return 0;
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return 0;
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}
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}
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