Author: Niall

Response Times and Number of Requests

As we approach the Fall semester, traffic is starting to ramp up. With the greater amount of data we can more confidently draw some conclusions. While the addition of CPUs to the application servers had a definite, measurable positive effect on system load, this did not translate into much, if any, of an impact on […]

Application Response Time

A quick update on application response times. If you recall, we recently added additional CPU to our application servers: On 8/8, Scott assigned two additional CPUs to ist-wp-app-prod02 On 8/11, Scott assigned two additional CPUs to ist-wp-app-prod01 and ist-wp-app-prod03 Here’s an updated chart with some additional data. Whereas our last post detailing response times suffered […]


I’ve create a Github repos: … for housing tools and utilities we create for our performance analysis. Right now it contains only one script,, which I used to calculate the response time percentiles referenced in my last post. The “scripts” directory is intended to contain executable, installable scripts, that is, scripts that we […]

Effect of Additional CPU on Page Response Time

One of the major measurements we’re going by is the page response time, as measured by the Apache log files. With Dick’s help, I’ve pulled the log data from all three application servers for the time period of 8/5 through 8/11, and calculated the response times at the 90th, 95th, and 99th percentiles. There are […]

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 […]

Sampling memcached statistics

We recently launched a new environment for our WordPress CMS, making major changes to both the hardware (bare metal to VMs) and software (file-based WP Supercache to memcached-backed Batcache). Unfortunately, we’re having performance issues. Page response times are significantly down, and several intensive activities cannot be completed (fortunately these are rare and infrequently performed). We’ll […]