On Thu, 2011-07-14 at 10:26 +0300, Pekka Enberg wrote: > On 07/13/2011 04:00 PM, Pekka Enberg wrote: > >> On Wed, Jul 13, 2011 at 3:57 PM, Avi Kivity<avi@xxxxxxxxxx> wrote: > >> >> We'd like to keep 8250 emulation because it's the most robust method > >> >> for getting data out of the kernel when there's problems. It's also > >> >> compatible with earlyprintk and such. > >> > > >> > What do you hope to gain from the optimization? 100ms less boot time? > >> > >> Hmm? I use serial console for logging into the guest and actually > >> using it all the time. > > On 7/13/11 4:32 PM, Avi Kivity wrote: > > Just how fast do you type? > > > > It's not enough to make something faster, it has to be slow to being > > with. The interface is good, but use it where it helps. > > I don't know why you bring up serial console input here. Sasha's > original KVM_IOEVENTFD_FLAG_PIPE patch clearly stated: > > A simple example for practical use is the serial port. we are not > interested in an exit every time a char is written to the port, but > we do need to know what was written so we could handle it on the > guest. > > So it's talking about the serial console output, not input. Yes, I have originally thought of doing the pipefd interface to prevent the overhead caused by console intensive benchmarks on actual benchmarks. It's funny how much slowness spinning the cursor or printing a table incurs. -- Sasha. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
