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Re: Running the test suite faster.

From: Philip Martin <philip_at_codematters.co.uk>
Date: 2007-11-03 19:03:42 CET

"Justin Erenkrantz" <justin@erenkrantz.com> writes:

> This is a relatively recent Mac Mini (2x 1.8GHz; Core Duo T2400)
> running Ubuntu 7.10. My MBP on Mac OS X is a 2.33 C2D. Neither are
> old machines.
>
> Are your 20 second tests run off a RAM drive or something? I'm

No, I'm using a real disk-based filesystem.

> running off the local HDD and not doing parallel runs - straight 'make
> check' out-of-the-box.

This is a new desktop, Core2Duo E4500 2.2GHz 2MB cache, 2G RAM, a
single SATA drive, running Debian/stable and using ext3 mounted
noatime. That's a new, low-end, Core2Duo.

> Here is 'time' output from a complete 'make check' run (46 minutes):
>
> 186.27user 135.30system 46:05.98elapsed 11%CPU (0avgtext+0avgdata 0maxresident)k
> 0inputs+0outputs (0major+13369289minor)pagefaults 0swaps

Running 'time make check' gives

real 9m23.409s
user 3m46.318s
sys 2m41.606s

(revert_tests.py 15 and 17 failed)

More CPU than you, but that's a non-optimised, pool-debugging build.
I think your machine should be able to run the tests much faster, my
first guess would be disk IO, you could try noatime if you are not
already using it.

> Again, there is no statistical difference between /dev/random and
> /dev/urandom for me on ra_serf / ra_local. So, I doubt it's entropy
> as urandom shouldn't be blocked by entropy.
>
> If it's ra_svn, then if you are using the MD5-CRAM authentication,
> then that would be a likely culprit. Using SASL with PLAIN would
> avoid that - perhaps we should configure out testsuite to do that.

Yes, the slowdown on my machine occurs with non-SASL ra_svn, using
SASL is another way to speed it up.

> However, if it is just ra_svn, that wouldn't explain Karl seeing a
> multi-factor speed-up on ra_dav or ra_local by changing the entropy
> source. -- justin

Different hardware 'generates' entropy at different rates, it's
possible that a machine that generates entropy slowly might have a
problem merely creating repository UUIDs, particularly if it otherwise
runs the tests quickly. Another possibility is that Karl's machine
may be running some other process, unconnected with the testsuite,
that drains the entropy pool.

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Received on Sat Nov 3 19:03:57 2007

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