[tor-bugs] #11791 [Tor]: Our zlib deflate objects require lots of memory per directory connection

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#11791: Our zlib deflate objects require lots of memory per directory connection
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     Reporter:  nickm    |      Owner:
         Type:  defect   |     Status:  new
     Priority:  normal   |  Milestone:  Tor: 0.2.6.x-final
    Component:  Tor      |    Version:
   Resolution:           |   Keywords:  tor-relay, zlib, 025-backport,
Actual Points:           |  026-triaged-1
       Points:           |  Parent ID:
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Comment (by nickm):

 I tried some experiments on microdescriptors, and found that for those, we
 seem to be able to lower windowbits with not much real damage to our
 compression ratio.  We could probably take windowbits down to 11 and not
 lose more than a few percent.  More tests needed though.

 For the performance hit of lowering memLevel: it didn't seem too bad to
 take it down to 7, but at 6 we took a 10% hit. (At windowbits==13, input
 size ==65536, level =8.)

 Another possibility is to investigate the average number of desciptors or
 microdescriptors we serve per request.  I'd note that for a 1024-byte
 input, lowering memLevel doesn't actually hurt performance at all, and
 lowering the compression ratio doesn't really waste that many bytes.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/11791#comment:5>
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