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From Apache subversion Wiki <comm...@subversion.apache.org>
Subject [Subversion Wiki] Trivial Update of "MeasuringRepositoryPerformance" by StefanFuhrmann
Date Sun, 13 Jul 2014 18:24:56 GMT
Dear Wiki user,

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The "MeasuringRepositoryPerformance" page has been changed by StefanFuhrmann:
https://wiki.apache.org/subversion/MeasuringRepositoryPerformance?action=diff&rev1=1&rev2=2

Comment:
typo

  
  With this [[https://svn.apache.org/repos/asf/subversion/trunk/tools/dev/benchmarks/RepoPerf/copy_repo.py|python
script]], you also get random data files of up to the specified size being written in between
revisions.  Those get deleted once the copy is complete. Depending on the OS / SAN heuristics,
this may mimic the presence of other repositories growing as the copied one does.  Moreover,
multiple repositories get copied at once in a round-robin interleaved scheme, i.e. copy rev
0 of all repositories, then rev 1 of all repositories, etc.
  
- The spacing parameter should be equal to the average revision data being written to other
repos for each revision / packed shard copy round.  IOW something like (total size of "missing"
repos) / (number of revs in copied repos).  As that may result in too much transiently disk
space being allocation, you may use 128 here.  That plays well with typical RAID strip and
OS prefetch sizes.
+ The spacing parameter should be equal to the average revision data being written to other
repos for each revision / packed shard copy round.  IOW something like (total size of "missing"
repos) / (number of revs in copied repos).  As that may result in too much transiently disk
space being allocated, you may use 128 here.  That plays well with typical RAID strip and
OS prefetch sizes.
  
  == What to test ==
  Before you conduct performance tests, you need to decide upon the scenarios as well as what
kind of conclusions you want to be able to draw from the results.  For the latter, it is often
useful to identify the components and settings involved and to be able to isolate their contribution.

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