Additional CPU Added to App Server

We added two additional cores to one of our three WordPress application servers to see what kind of effect it had on performance. This particular app server had been sustaining higher system load for the past couple of weeks, which we believe was caused by uneven memcached key distribution (the application servers also run our memcached servers).

The initial news is that system load dropped significantly on the server.

WordPress Load

The server is represented by the yellow line. We can also see that the massive load spikes appear to have evened out.

Unfortunately, most of the WordPress team was in training yesterday (and also today), so we’ve still got a lot of investigation and analysis to do. For example, the cache distribution was changed when we restarted the server to add CPU, and this may be contributing to the lower load.