[tahoe-lafs-trac-stream] [tahoe-lafs] #1545: add readv() API to immutable-share storage-server protocol, use in downloader

tahoe-lafs trac at tahoe-lafs.org
Mon Sep 26 23:53:43 PDT 2011


#1545: add readv() API to immutable-share storage-server protocol, use in
downloader
------------------------------+-------------------------
     Reporter:  warner        |      Owner:
         Type:  enhancement   |     Status:  new
     Priority:  major         |  Milestone:  undecided
    Component:  code-storage  |    Version:  1.9.0a2
   Resolution:                |   Keywords:  performance
Launchpad Bug:                |
------------------------------+-------------------------

Comment (by warner):

 early results suggest that doing this would speed up high-k immutable
 downloads by about 24%. For example, k=54 with trunk takes roughly 414s to
 download a 100MB file (6 servers, 3 hosts, LAN connections). When basic
 readv() is used, this drops to 317s. For small k (like the default k=3),
 the effect is less clear, however there still seems to be a significant
 improvement (k=3 trunk 100MB takes maybe 38s, with-readv takes 32s).

 The effect is roughly halfway between unmodified trunk CHK and trunk MDMF
 (which prefetches the whole block_hash_tree and doesn't even have a
 crypttext_hash_tree).

-- 
Ticket URL: <http://tahoe-lafs.org/trac/tahoe-lafs/ticket/1545#comment:1>
tahoe-lafs <http://tahoe-lafs.org>
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