[tahoe-dev] [tahoe-lafs] #983: high CPU load on storage servers when uploading large mutable file

[tahoe-lafs]

#983: high CPU load on storage servers when uploading large mutable file
------------------------------+---------------------------------------------
     Reporter:  zooko         |       Owner:                            
         Type:  defect        |      Status:  reopened                  
     Priority:  major         |   Milestone:  undecided                 
    Component:  code-storage  |     Version:  1.6.0                     
   Resolution:                |    Keywords:  performance mutable upload
Launchpad_bug:                |  
------------------------------+---------------------------------------------
Changes (by zooko):

  * status:  closed => reopened
  * resolution:  fixed =>


Comment:

 maco package foolscap 0.5.1 for Ubuntu Lucid and !ChosenOne ran some
 experiments. His experiments showed that storage servers running foolscap
 0.5.1 did ''not'' accept shares of large mutable files faster than when
 they were running foolscap 0.4.2:

 While using 0.4.2:

 http://pastie.org/private/39twijkh8ip5ffzeiog
 {{{
     * Current Size: 41943040
           o Per-Server Response Times:
                 + [uydf5ds4]: 846ms
 }}}
 http://pastie.org/private/ofjv1dgmw44q44nt1jo4nw
 {{{
     * Current Size: 104857600
           o Per-Server Response Times:
                 + [uydf5ds4]: 6.07s
 }}}
 http://pastie.org/private/zcns60kuyx2rjdpfhnl2g
 {{{
     * Current Size: 209715200
           o Per-Server Response Times:
                 + [uydf5ds4]: 20 seconds
 }}}
 After upgrading to foolscap 0.5.1:

 http://pastie.org/private/g9xfymdchzvxqpkoxdowkq
 {{{
     * Current Size: 209715200
           o Per-Server Response Times:
                 + [uydf5ds4]: 36 seconds
 }}}
 http://pastie.org/private/fnkdkn7jkhm7yriidkx0ba
 {{{
     * Current Size: 209715200
           o Per-Server Response Times:
                 + [uydf5ds4]: 69 seconds
 }}}
 Hm. In fact, the pattern, if there is one, is that it takes twice as long
 every time he uploads a file!

-- 
Ticket URL: <http://allmydata.org/trac/tahoe/ticket/983#comment:7>
tahoe-lafs <http://allmydata.org>
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