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Re: Performance Results on Windows

From: Ivan Zhakov <ivan_at_visualsvn.com>
Date: Wed, 13 Aug 2014 22:21:21 +0400

On 23 July 2014 17:19, Stefan Fuhrmann <stefan.fuhrmann_at_wandisco.com> wrote:
> Updated and final results:
> * svnadmin dump results now included, f6 / f7 is +/-20%
> * fixed anomaly with ra_serf, results consistent with previous findings
> 'null-export' tests have been rerun and old results been replaced
> * added a page on how 'null-export' reacts on cache configuration
> to get a better picture of how cache size, ra layer and block-read
> interact when caches are hot. Data for small or cold caches has
> already been in covered in other tests.
I just want to note that your conclusions don't point the fact that
there is performance degradation in many case:
1. 'svn log -v' for bsd-nopack repository over svn:// in 'FAST'
configuration is 51% slower
2. 'svn export' for ruby-nopack repository over file:// in 'FAST'
configuration is 23% slower

So I ask for unbiased performance tests. As far as I remember, you
advertised the 2x-10x performance improvement on the hackaton in
Berlin (that is supposed to be already achieved at the time of
presentation). Then we have found (and fixed) several cases of
performance degradation. But you didn't tell us about these cases. So
I consider your performance measurements as biased.

I'm still getting bad numbers in my tests. But obviously, my tests can
be considered as a biased too because I am strongly against this
feature for many reasons. That's why we need an unbiased performance

I think that the unbiased tester should pay attention to ensure both
the following:
1) there is *significant* performance improvement for some realistic cases
2) there are no performance degradation in *all the typical Subversion
usage configurations* (including the worst ones).

It seems that CollabNET and other hosting providers possibly have one
of the worst configuration for log-adressing feature. Multiple users
access over HTTP to a number of gigabyte-sized repositories (so there
are no enough memory for enormous caches). Authorization is enabled
(my tests shows that this is important). Apache httpd uses prefork MPM
(that should eliminate the caches).

Also I'd like to note that your method to achieve 'Cold' state on
Windows is totally wrong: you're basically allocating *all* available
memory by 'ClearMemory' tool making OS starving on all resources [1].
It's abnormal situation for operating system. So your 'Cold' state
results are irrelevant.

[1] https://svn.apache.org/repos/asf/subversion/trunk/tools/dev/benchmarks/RepoPerf/ClearMemory.cpp

Ivan Zhakov
CTO | VisualSVN | http://www.visualsvn.com
Received on 2014-08-13 20:22:09 CEST

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