Mark Phippard <markphip_at_gmail.com> wrote on 05/13/2009 11:37:57 AM:
> On Wed, May 13, 2009 at 12:31 PM, Chris Lieb
> <chris.lieb+nospam_at_gmail.com> wrote:
>
> > I noticed in the release notes for Subversion 1.6 that one of the new
> > features is caching for FSFS repositories using memcached. When I
> > install subversion-1.6.* on Gentoo, part of the post-install notes say
> > that, in order to use the caching, I need to install memcached,
> > configure and start it, then configure my repositories to use it.
> >
> > I have installed memcached, configured it to have a cache of 256MB and
> > listen on 0.0.0.0:11211, and started it. Running memcached-tool
locally
> > gives me an empty list of cached objects. Checking out some files
using
> > http, svn+ssh, and file RAs does not seem to cause any cache to be
> > built, as memcached-tool still displays an empty cache pool.
> >
> > What do I have to do to get memcached support enabled for my
Subversion
> > repositories? I haven't been able to find a thing using Google other
> > than that the feature was added in Subverison 1.6.
>
> When I create a new fsfs repository with SVN 1.6, inside the "db"
> folder is a file named fsfs.conf. This contains the memcached
> settings.
Anyone do any performance analysis of using memcached? I'm not
seeing much (if any) benefit, but that could be due to a fairly
high performance SAN storage solution for storage.
Here are my numbers:
no cache: 10 min 33 sec
cold cache: 10 min 30 sec
hot cache: 10 min 26 sec
(The differences are statistically insignificant.)
This is for a single repo with 600M of data in 30k files.
Server cpu usage seemed consistent with and without
the cache. I (unfortunately) wasn't able to monitor disk I/O.
I was using a 2G memcached, of which it used around 600M for the
cache. Oddly enough, monitoring memcached showed only a 70%
cache hit when repeatedly downloading the same repository.
(I would have expected a 100% hit ratio from the memcached side.)
memcached was running on the same server as apache for the tests.
(A quad core 64-bit AMD server running solaris 10 x86. 4G of RAM
with storage on an enterprise SAN connected with fiber.)
svn 1.6.2
httpd 2.2.11
apr 1.3.3
apr-util 1.3.4
neon 0.28.4
memcached 1.2.8
Test repository was created and populated with svn 1.6.2.
I also noticed if no memcached servers were running, but a repository
was configured to use it, a checkout would fail during the checkout
of the first directory. It probably should continue to work as
if no cache was configured instead of failing...
Anyone else see some better results?
Kevin R.
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Received on 2009-05-18 21:33:25 CEST