[tahoe-lafs-trac-stream] [Tahoe-LAFS] #3952: Benchmarks for basic immutable Tahoe operations (upload and download)

[Tahoe-LAFS]

#3952: Benchmarks for basic immutable Tahoe operations (upload and download)
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     Reporter:  itamarst     |      Owner:
         Type:  enhancement  |     Status:  new
     Priority:  normal       |  Milestone:  HTTP Storage Protocol
    Component:  unknown      |    Version:  n/a
   Resolution:               |   Keywords:
Launchpad Bug:               |
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Comment (by itamarst):

 For a small 2000 byte file with a single share uploaded to a single node,
 an upload is 3 sequential HTTP requests, and a download is 4 sequential
 HTTP requests. So with high latency this gets quite slow.

 Next, I tested over loopback, but with RTT latency of 60ms (30ms one way)
 artificially added. Bandwidth is quite high, so not likely to be a
 bottleneck.

 * When uploading the 2000 byte file, upload time was 300ms, and download
 was 300ms.
 * When uploading a 2MB file, upload time was 300ms, and download time was
 3200ms.

 Thus:

 * Immutable uploads use parallelism, and main bottleneck is latency, which
 only impacts small files. However, sequential uploads will have minimal
 time no matter what the bandwidth.
 * Immutable downloads have a latency hit, but even worse are not utilizing
 parallelism well, so large files suffer from latency hit even when
 bandwidth is not a bottleneck.

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Ticket URL: <https://tahoe-lafs.org/trac/tahoe-lafs/ticket/3952#comment:2>
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