On 2011-06-20 10:12, Avi Kivity wrote: > 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. > > Signed-off-by: Avi Kivity <a...@redhat.com> > --- > > v2: drop unportable fputc_unlocked > > hw/vga.c | 13 ++++++++++--- > 1 files changed, 10 insertions(+), 3 deletions(-) > > diff --git a/hw/vga.c b/hw/vga.c > index d5bc582..97c96bf 100644 > --- a/hw/vga.c > +++ b/hw/vga.c > @@ -2349,15 +2349,19 @@ int ppm_save(const char *filename, struct > DisplaySurface *ds) > uint32_t v; > int y, x; > uint8_t r, g, b; > + int ret; > + char *linebuf, *pbuf; > > f = fopen(filename, "wb"); > if (!f) > return -1; > fprintf(f, "P6\n%d %d\n%d\n", > ds->width, ds->height, 255); > + linebuf = qemu_malloc(ds->width * 3); > d1 = ds->data; > for(y = 0; y < ds->height; y++) { > d = d1; > + pbuf = linebuf; > for(x = 0; x < ds->width; x++) { > if (ds->pf.bits_per_pixel == 32) > v = *(uint32_t *)d; > @@ -2369,13 +2373,16 @@ int ppm_save(const char *filename, struct > DisplaySurface *ds) > (ds->pf.gmax + 1); > b = ((v >> ds->pf.bshift) & ds->pf.bmax) * 256 / > (ds->pf.bmax + 1); > - fputc(r, f); > - fputc(g, f); > - fputc(b, f); > + *pbuf++ = r; > + *pbuf++ = g; > + *pbuf++ = b; > d += ds->pf.bytes_per_pixel; > } > d1 += ds->linesize; > + ret = fwrite(linebuf, 1, pbuf - linebuf, f); > + (void)ret; > } > + qemu_free(linebuf); > fclose(f); > return 0; > }
Unrelated to this patch, but why is this function located in vga.c and not in console.c? Jan -- Siemens AG, Corporate Technology, CT T DE IT 1 Corporate Competence Center Embedded Linux