[tor-bugs] #16914 [Tor]: improve consensus download decompress performance

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#16914: improve consensus download decompress performance
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     Reporter:  teor         |      Owner:
         Type:  enhancement  |     Status:  needs_information
     Priority:  normal       |  Milestone:
    Component:  Tor          |    Version:  Tor: 0.2.6.10
   Resolution:               |   Keywords:  TorCoreTeam201509 Post027Freeze
Actual Points:               |  Parent ID:
       Points:               |
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Comment (by teor):

 Further notes from my tor-dev email:

 The micro descriptor consensuses are 1.2 MBytes, and the combined size of
 all cached microdescriptors is 2.9MBytes.

 The 5% difference between 70% and 75% is 61 KByte for the 1.2 MByte micro
 descriptor consensus, which is the largest individual file. This
 optimisation costs us nothing, except that if we cut it too close, and the
 compression ratio improves, we get a memory doubling and reallocation
 during decompression, which we’re trying to avoid. This would be most
 likely to happen in the full consensus decompression (currently 66%
 compression ratio on 1.4 MBytes), which is the one we care least about,
 because it's on the most powerful servers [citation needed].

 Do we want to go with the 70% option to save both RAM and reallocation
 performance?
 Or do we want to go with the 75% option to avoid reallocation, even if the
 ratio improves?

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/16914#comment:4>
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