[tahoe-lafs-trac-stream] [tahoe-lafs] #1844: slow download speeds

[tahoe-lafs]

#1844: slow download speeds
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 Reporter:  l3iggs       |          Owner:  davidsarah
     Type:  defect       |         Status:  new
 Priority:  normal       |      Milestone:  undecided
Component:  unknown      |        Version:  1.9.2
 Keywords:  performance  |  Launchpad Bug:
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 I have 2 storage servers and one client machine.[[BR]]
 storage-serverA = 4x1.6 GHz, 3GB of ram, on home lan[[BR]]
 storage-serverB = 2x2.3 Ghz, 31GB of ram, remote locaction[[BR]]
 client = 4x2.4 GHz, 4 GB of ram, on home lan[[BR]]
 I have[[BR]]
 k=1[[BR]]
 N=2[[BR]]
 h=2[[BR]]
 When I download a 104MB file from my cluster using[[BR]]
 wget http://localhost:$PORT/uri/$CAP [[BR]]
 wget reports that file transfer takes place at ~1.5M/s and completes in 67
 seconds[[BR]]
 In this example, storage-serverA (on my lan) transfers the entire file
 (see attached file dlStatus.html)[[BR]]
 During the transfer tahoe consumes 76% of one core of the CPU on storage-
 serverA. And 16% of one core of the CPU on client.[[BR]]

 The same file transferred using[[BR]]
 scp user at storage-serverA:/file[[BR]]
 takes place at ~12.3 MB/s and completes in 8 seconds.[[BR]]
 During this transfer, sshd consumes 103% of one core of the CPU on
 storage-serverA. And ssh consumes 22% of one core of the CPU on
 client.[[BR]]

 tahoe-lafs seems to be ~8x slower on a point to point transfer over my lan
 than ssh is.

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Ticket URL: <https://tahoe-lafs.org/trac/tahoe-lafs/ticket/1844>
tahoe-lafs <https://tahoe-lafs.org>
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