[tahoe-lafs-trac-stream] [tahoe-lafs] #1180: put more DYHBs into flight at once when K is larger
tahoe-lafs
trac at tahoe-lafs.org
Mon Apr 11 10:01:59 PDT 2011
#1180: put more DYHBs into flight at once when K is larger
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Reporter: zooko | Owner:
Type: defect | Status: new
Priority: major | Milestone: soon
Component: code- | Version: 1.8β
network | Keywords: easy immutable download performance
Resolution: | regression
Launchpad Bug: |
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Description changed by zooko:
Old description:
> As mentioned in comment:8:ticket:448, the new downloader code in v1.8.0
> will put at most 10 DYHBs into flight at once. This is perfect when
> {{{K=3}}}, but as {{{K}}} gets larger it is increasingly likely that the
> hardcoded limit of {{{10}}} will induce delay at the beginning of a
> download or cause the downloader to overlook a better-performing server.
> As Brian suggested on #448, a better limit would be something like {{{K *
> 3}}}.
>
> (Note: everyone that I know of uses the default settings of {{{K=3,
> M=10}}}. The theoretical maximum value of {{{K}}} is 256. I think there
> might be other problems with using {{{K}}} greater than about {{{100}}},
> such as a worse rate of a storage server failing during your download,
> but I'm not sure.)
New description:
As mentioned in comment:8:ticket:448, the new downloader code in v1.8.0
will put at most 10 DYHBs into flight at once. This is perfect when
{{{K=3}}}, but as {{{K}}} gets larger it is increasingly likely that the
hardcoded limit of {{{10}}} will induce delay at the beginning of a
download or cause the downloader to overlook a better-performing server.
As Brian suggested on #448, a better limit would be something like {{{K *
3}}}.
(Note: everyone that I know of uses the default settings of {{{K=3,
M=10}}}. The theoretical maximum value of {{{K}}} is 256. Since nobody has
tried it, we don't know if there are other problems with using {{{K}}}
greater than about {{{100}}}.)
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Ticket URL: <http://tahoe-lafs.org/trac/tahoe-lafs/ticket/1180#comment:4>
tahoe-lafs <http://tahoe-lafs.org>
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