On Wed, Mar 09, 2011 at 10:30:00AM -0800, Evan Martin wrote: > On Wed, Mar 9, 2011 at 6:18 AM, David Hill <dh...@mindcry.org> wrote: > >> Prefetch isn't mentioned in the HTTP spec at all. And I don't think > >> anyone was doing it back in the modem age. AFAIK, Google started doing > >> it with Chrome, and other people followed. > > > > If it is not mentioned in the spec, I think it should be optionized > > then, not hardcoded. ?Google started doing it with Chrome, but was it a > > performance booster, or (imo) a way to track users even more? > > Your conspiracy theory is impressive, but as far as I know Google > doesn't get to observe the DNS traffic of every person on the > internet. Maybe you know something about DNS that I don't. ;)
http://code.google.com/speed/public-dns/ just sayin' :-) > We did measure the benefit of DNS prefetching. When we prefetch a > hostname, we record the time that we needed to wait for the resolution > to complete. When we later do a real fetch for that host, we record > that the time we spent prefetching was a gain. You can see these > numbers in Chrome by visiting > about:histograms/DNS.ResolveSuccess > > For users who have opted in to reporting anonymous statistics, we send > those numbers (no hostnames, just the millisecond counts) to Google. > Looking at that data right now, I see that 10% of users' requests were > sped up by 400ms or more, which is huge in terms of web speed. > (Consider that you can't even start fetching subresources until you've > successfully made the initial connection the host.) > There's a screenshot of some older data here: > http://blog.chromium.org/2008/09/dns-prefetching-or-pre-resolving.html Not sure I read the results correctly but I seem to only see raw DNS lookup speed gain. Not overall "user visible page load times". So since I am not sure I get the results I won't comment further on it. > > > I have tested this patch and the performance boost is unbelievable. > > I guess on IRC Marco was saying that DNS on OpenBSD is single Uhm, I don't recall being on IRC ;-) > threaded? Maybe I misunderstood. It would sound like a bug in > libsoup to me if so. Certainly if you can't resolve DNS in parallel I > would expect it's better to do fewer resolutions. The OpenBSD libc resolver is a single pipe and it obviously exacerbates the problem however, I use a resolver that parallelizes things. Unfortunately I seem to mostly use really crappy nameservers so I see issues all the time. > For the record, I fully support you adding the option to disable > prefetching. I just hope that you want to do it for a good reason. Sure, we agree here. I have a number of reasons from performance to security to paranoia to bandwitdh etc. The fact that I am paranoid doesn't mean they aren't watching :-) _______________________________________________ webkit-gtk mailing list webkit-gtk@lists.webkit.org http://lists.webkit.org/mailman/listinfo.cgi/webkit-gtk