[drupal-devel] Drupal cache statistics

[Dries Buytaert]

Hello world,

I did some more experiments:

1. Enabled strict caching on drupal.org
2. Enabled loose caching on drupal.org (300 sec. delay, default)
3. Enabled loose caching on drupal.org (600 sec. delay)

Per configuration we measured more than 150.000 page requests.

Results
-------

If we look at the cache miss percentages of anonymous user requests  
only (excl. authenticated users) we get:

1. Strict       : 66%
2. Loose, 300ms : 65%
3. Loose, 600ms : 64%

If we look at the average number of pages served between two flushes  
(excl. authenticated users) we get:

1. Strict       : 280 pages/flush
2. Loose, 300ms : 182 pages/flush
3. Loose, 600ms : 327 pages/flush

Conclusion
----------

1. Loose caching has NO effect on drupal.org's page cache.
2. Loose caching has NO well-defined effect on drupal.org's flush ratio.

Possible solutions
------------------

Unless we can serve 2000+ pages/flush (random estimate), the cache  
will never be efficient.

1. Rework loose caching to flush less frequently.
2. Flush partially.
3. Maybe there is a bug?
4. Remove 'loose caching'?

--
Dries Buytaert  ::  http://www.buytaert.net/