[tor-bugs] #24368 [Core Tor/Tor]: A zstd-compressed cached-microdesc-consensus is 2% larger than a gzipped one (was: A zstd-compressed cached-microdesc-consensus is 1.5% larger than a gzipped one)

[Tor Bug Tracker & Wiki]

#24368: A zstd-compressed cached-microdesc-consensus is 2% larger than a gzipped
one
-------------------------------------------------+-------------------------
 Reporter:  teor                                 |          Owner:  (none)
     Type:  defect                               |         Status:  new
 Priority:  Medium                               |      Milestone:  Tor:
                                                 |  0.3.3.x-final
Component:  Core Tor/Tor                         |        Version:  Tor:
                                                 |  0.3.1.1-alpha
 Severity:  Normal                               |     Resolution:
 Keywords:  regression, compression, zstd, tor-  |  Actual Points:
  dir                                            |
Parent ID:                                       |         Points:  1
 Reviewer:                                       |        Sponsor:
-------------------------------------------------+-------------------------

Old description:

> Using the cached-microdesc-consensus that is:
> {{{
> valid-after 2017-11-21 11:00:00
> }}}
>
> I get the following results:
> {{{
> $ zstd cached-microdesc-consensus
> $ gzip -9 cached-microdesc-consensus
> $ du -h cached-microdesc-consensus*
> 1.9M    cached-microdesc-consensus
> 564K    cached-microdesc-consensus.gz
> 576K    cached-microdesc-consensus.zst
> }}}
>
> It's only 1.5% larger, but I thought zstd was meant to produce smaller
> consensuses than gzip?
> Or did I get the compression settings wrong?

New description:

 Using the cached-microdesc-consensus that is:
 {{{
 valid-after 2017-11-21 11:00:00
 }}}

 I get the following results:
 {{{
 $ zstd cached-microdesc-consensus
 $ gzip -9 cached-microdesc-consensus
 $ du -h cached-microdesc-consensus*
 1.9M    cached-microdesc-consensus
 564K    cached-microdesc-consensus.gz
 576K    cached-microdesc-consensus.zst
 }}}

 It's only 2% larger, but I thought zstd was meant to produce smaller
 consensuses than gzip?
 Or did I get the compression settings wrong?

--

Comment (by teor):

 Oops, that's 2% larger.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/24368#comment:1>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
The Tor Project: anonymity online