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Re: 1.7 timing tests: update great, checkout needs work, upgrade horrible

From: Hyrum K. Wright <hyrum_wright_at_mail.utexas.edu>
Date: Thu, 9 Dec 2010 09:03:49 -0800

On Mon, Dec 6, 2010 at 8:01 PM, Blair Zajac <blair_at_orcaware.com> wrote:
> I'm working with a client and they have a large source source code checkout
> that takes over 10 minutes do to an svn update.  Their 1.6.x working copy
> size is 3.6 GB with 74,000 files and 19,230 directories.  The amount of IO
> to do all the locking and reading entries files is taking a significant
> amount of time.
> They are looking at techniques to speed up updates, as it's a significant
> productivity drain, but it's much slower than git-svn.
> So we thought we'd try the 1.7 client at r1042760.
> The good news is that "svn update" is significantly faster than 1.6,
> dropping from over 10 minutes to 3:07 with a cold cache and 0:48 with a warm
> cache.  This is great.
> Unfortunately, it looks like checkout times have gotten worse.  On a SATA
> disk with ext3:
>        Clock           System          User
>        time            time            time
> 1.6      5:41            94.1           58.9
> 1.7     12:20           106.2           99.9
> I noticed that doing an strace of the checkout leads to a 1.3 GB file with
> 1.6.x and 4.1 GB with 1.7.x, so many more operations.
> I haven't been following 1.7 performance lately, but are we aware of this?
>  Are there any obvious performance fixes here?
> I realize that 1.7 is a ways away, but the scalability svn update brings to
> svn checkouts is a significant win.
> We also tried an 1.6.x checkout followed by a 1.7 upgrade.  Last I looked
> the process it had 110 minutes of CPU time.  Definitely not worth upgrading,
> faster to do a fresh checkout, even with the checkout performance slower
> than 1.6.x.

This feels really bizarre. Isn't checkout just "create an incomplete
directory, then update it"? As such, one would think the performance
would be comparable. Bizarre indeed....

Received on 2010-12-09 18:04:29 CET

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