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Re: Performance

From: William Nagel <bill_at_stagelogic.com>
Date: 2005-09-12 22:24:09 CEST

On Sep 12, 2005, at 2:21 PM, Paul Koning wrote:

> I'm doing tests of CVS vs. Subversion.
>
> The first test is to checkout a full working directory, on a rather
> large repository (35,000 revisions, and the CVS working directory is
> foo MB).

My brain got an NaN parse error on your working directory size. ;-)

>
> In CVS that takes 10 minutes. In Subversion, it takes 46 minutes.
> I'm not surprised it takes a little longer, after all SVN has to write
> two copies (the regular one and the clean one in .svn). But that
> difference is quite surprising.

This is a fairly well-known issue. Because of design difference
between Subversion and CVS, checkouts can take significantly longer
under Subversion. Just about everything else runs faster though, so
it's a tradeoff that most people consider acceptable (given that
you're not normally going to check out a working copy very often).

>
> The other puzzle is that svn sits for a minute or two at the end,
> without producing any output and without any significant activity that
> I can see. CPU time goes up just a little (17:02 at the end of the
> activity, and then 17:04 a little later). The server isn't doing
> anything (the httpd thread shows 11:25 CPU time). What's going on
> there?
>
> Is it reasonable for things to take this long?

Probably. Of course, I have little experience with repositories of
size "foo" so I can't say for sure. If you give a real size people
may have an easier time responding with comparisons to their own
experiences. :-)

>
> By the way, I changed /dev/random to be /dev/urandom given the earlier
> comments about a possible reason for things to get stalled. (Not that
> this makes any sense -- what possible use does the server have for
> strong random numbers in this process???) So that definitely isn't a
> consideration. Actually, I ran the test several times, before and
> after that change; the timing was identical.

I believe the random numbers are used for SSL, but I'm not positive
on that. Assuming I'm right, then it should be a non-issue if you're
not using SSL.

-Bill

>
> Subversion 1.2.3, Apache 2.0.54. The machine runs Linux 2.4.21 on a
> quad processor Xeon, 1 GB memory.
>
> paul
>
>
>
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Received on Mon Sep 12 22:26:16 2005

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