On Wed, Mar 9, 2011 at 6:18 AM, David Hill <[email protected]> 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. ;) 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 > I have tested this patch and the performance boost is unbelievable. I guess on IRC Marco was saying that DNS on OpenBSD is single 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. 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. _______________________________________________ webkit-gtk mailing list [email protected] http://lists.webkit.org/mailman/listinfo.cgi/webkit-gtk
