Inconsistent behavior

WordPress Nginx
#1

Without getting into the details of the server, most WP sites show this inconsistent behavior:

I'm logged in so fast_cgi doesn't cache and I see something like:

This page loaded in 24.369 seconds with 40 database queries.

Then I refresh and get:

This page loaded in 0.307 seconds with 40 database queries.

The point is its random. Sometimes I get really high times consecutively, sometimes consecutively low load times, what could be the cause?

MYSQL query cache is huge and has plenty of available space as does the APC cache (in case it matters).

#2

How much time it takes to generate a page depends on many things. Even if page is same, concurrent connections/workload can affect page-generation time.

Using InnoDB everywhere may help http://rtcamp.com/wordpress-nginx/tutorials/mysql/myisam-to-innodb/

#3

I know what you mean but its a 16GB RAM machine and its using 2GB! Everything is "optimized", using nginx + fastcgi_cache + php5-fpm + APC (1GB cache) and a "well-configured" MYSQL with a pretty big query cache.

The machine is so idle, you can't have less to do so I was expecting consistency. There are maybe 15 domains hosted on it with a total of max. a few hundred visitors per day. Really low volume. PHP is set up to use the ondemand process manager.

On the other hand, I just reloaded this page a few times: http://rtcamp.com/wordpress-nginx/

and got from: It took 62 queries executed in 0.639 seconds to It took 62 queries executed in 31.540 seconds so I'm not that worried anymore :-)

#4

@ovidiu

You are seeing variations because we are not using page-caching for logged-in users.

I guess those number depends on object/database-caching which is handled by W3 Total Cache here.

#5

Yeah, I understand. I just thought a system with minimal load should/would give results that are much closer and don't show such big variances and more consistency.

#6