[tahoe-dev] Tahoe performance

Francois Deppierraz francois at ctrlaltdel.ch
Fri Feb 13 08:11:48 UTC 2009

Hi Brian,

Brian Warner wrote:

> Yeah, this is disappointing. Our automated speed tests [1] show an upload
> speed between 0.8MBps and 1.4MBps, using 100MBps local bandwidth, which is
> much slower than we'd like. The upload speed used to be closer to 2.0MBps
> (and the download speed was nearly 5MBps) a year ago, before we reduced the
> maximum segment size to 128KiB (to improve alacrity). This hurts throughput
> because we aren't yet using a windowing protocol to upload shares, so we burn
> a round-trip time for each segment, so smaller segments means more time
> wasted.

It means that my upload speed (0.125 MBps) 180ms away from allmydata.com
servers is still 8 times slower than your automated speed tests.

Does it means that latency hurts throughput that much ?

For the record, uploading plaintext directly on the webapi of a
production allmydata.com node allows me to saturate my upstream
bandwidth. Thanks to TCP's efficient flow control.


More information about the tahoe-dev mailing list