From f8e378f27f2a8b99bf9be0a9168ba0ea19eeb740 Mon Sep 17 00:00:00 2001 From: Avi Kivity Date: Mon, 20 Jun 2011 11:12:47 +0300 Subject: 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 Signed-off-by: Avi Kivity Signed-off-by: Anthony Liguori --- hw/vga.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/hw/vga.c b/hw/vga.c index 124295ae52..0f54734624 100644 --- a/hw/vga.c +++ b/hw/vga.c @@ -2346,15 +2346,19 @@ 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; @@ -2366,13 +2370,16 @@ 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; } -- cgit v1.2.3