On Sat, 26 Nov 2011, Ángel González wrote:
On 10/11/11 03:24, Andrew Daviel wrote:
When downloading a large file over a high-latency (e.g. long physical
distance) high-bandwidth link, the download time is dominated by the
round-trip time for TCP handshakes.
Using the "range" header in HTTP/1.1, it is possible to start multiple
simultaneous requests for different portions of a file using a
standard Apache server, and achieve a significant speedup.
I wondered it this was of interest as an enhanscement for wget.
I think setting a big SO_RCVBUF should also fix your issue, by using big
window sizes, and it's cleaner.
OTOH, you need support from the TCP stack, and that won't trick
per-connection rate limits that may be
limiting you in the single-connection case.
Yes, jumbo frames work well over a private link like a lightpath. I'd
been thinking of something that would work on the unimproved public
internet.
I had been thinking of speeding up transfers to e.g. a WebDAV repository
on another continent, but I became recently aware of "download
accelerators" designed primarily to thwart bandwidth
allocation/throttling. Interestingly Wget is listed on the Wikipedia page
as a "download manager", implying it can already do this.
http://en.wikipedia.org/wiki/Download_acceleration
--
Andrew Daviel, TRIUMF, Canada