[tahoe-dev] Tahoe-LAFS v1.8.0 potentially delayed by performance issue

[Zooko O'Whielacronx]

Folks:

It seems like Tahoe-LAFS v1.8.0c2 downloads this movie file:

http://127.0.0.1:3456/file/URI%3ACHK%3A4klgnafrwsm2nx3bqy24ygac5a%3Acrz7nhthi4bevzrug6xwgif2vhiacp7wk2cfmjutoz2ns3w45qza%3A3%3A10%3A1490710513/@@named=/bbb-360p24.i420.lossless.drc.ogg.fixed.ogg%2Bbbb-24fps.flac.via-ffmpeg.ogg

About 1/3 as fast as Tahoe-LAFS v1.7.1 downloads the same file from
the same grid (the public Test Grid circa today).

We're investigating (see ticket #1170 for our progress) and we might
delay the final release of Tahoe-LAFS v1.8.0 (previously planned for
August 15 -- this Sunday). This might turn out to require a patch
added on top of Tahoe-LAFS v1.8.0c2 to make it so it isn't such a
significant performance regression in this case. Or it might turn out
that this is a really peculiar situation which will almost never occur
for any other user and we'll decide to release v1.8.0c2 as v1.8.0
final.

If you care about immutable download performance, please compare
v1.8.0c2 to v1.7.1 on your network with your files! And report your
results to this list. Nathan Eisenberg has done so [1], and shown that
v1.8.0c1 was substantially *faster* than v1.7.1 for his tests. (Note
that 1.8.0c1 and 1.8.0c2 are identical with regard to immutable file
download speed.) Earlier Kyle Markley did some benchmarking of v1.7.1
[2, 3, 4, 5, 6, 7, 8, 9], but nobody has yet replicated his experiment
using v1.8.0c2. I have done quite a bit of benchmarking this one
particular file from my office (SimpleGeo) and home, and my results
are all on #1170.

Regards,

Zooko

[1] http://tahoe-lafs.org/pipermail/tahoe-dev/2010-August/004930.html
[2] http://tahoe-lafs.org/pipermail/tahoe-dev/2010-July/004776.html
[3] http://tahoe-lafs.org/pipermail/tahoe-dev/2010-July/004781.html
[4] http://tahoe-lafs.org/pipermail/tahoe-dev/2010-July/004782.html
[5] http://tahoe-lafs.org/pipermail/tahoe-dev/2010-July/004786.html
[6] http://tahoe-lafs.org/pipermail/tahoe-dev/2010-July/004811.html
[7] http://tahoe-lafs.org/pipermail/tahoe-dev/2010-July/004808.html
[8] http://tahoe-lafs.org/pipermail/tahoe-dev/2010-July/004838.html
[9] http://tahoe-lafs.org/pipermail/tahoe-dev/2010-August/004853.html

http://tahoe-lafs.org/trac/tahoe-lafs/ticket/1170# does new-downloader
perform badly for certain situations (such as today's Test Grid)?