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>