The webapp runs in Tomcat and has a servlet which returns a JSON response after looping to generate the JSON to cause CPU computation time as if the service were doing real work. It results in a lot of iteration and string creation activity – things web services do a lot of.

ApacheBenchmark (ab) was used as the test client to simulate traffic and capture statistics.

The instance types tested were m2.2xlarge, m2.4xlarge, cc1.4xlarge, and cc2.8xlarge.

The tests determined that the cc2.8xlarge instance type – though the most expensive by unit – is potentially the most cost effective type to use when serving large volume traffic involving a cluster of servers.

The cost to serve 1000 requests/second at a response time of approximately 18ms for each instance type is:

• m2.2xlarge: $1.98
• m2.4xlarge: $2.48
• cc1.4xlarge: $1.36
• cc2.8xlarge: $1.19

Of course, this test is very simplistic and ignores a wide variety of variables, but it demonstrates that the cc1 and cc2 boxes are well worth the time to evaluate for production application usage for achieving cost/performance efficiency.

The following graphs show the test results that were used to calculate the above costs.

Results per Second with Increasing Concurrency

This demonstrates how the 32 CPU cores on the cc2.8xlarge enable significantly higher throughput.

Time per Request (ms) with Increasing Concurrency

This shows how the response time degrades with increasing thread counts and how the larger boxes (particularly the cc2) scale better.

Spreadsheet

This screenshot of the spreadsheet shows the cost calculations at each level of concurrency.

The hi-lighted green is considered the optimal “ceiling” beyond which performance degrades and throughput plateaus. This point is considered the high-water-mark that can be used to determine the number of machines in a cluster needed to serve a given amount of traffic and thus allow comparison of different machines.

Price per 1000 Requests per Second with Increasing Concurrency

This scatter chart shows the cost to serve 1000 requests per second at increasing levels of concurrency on each instance type.

Overall, the performance of the cc1 and cc2 boxes are impressive and their cost/performance appears to be far better than the m2 instances.

The raw results of the tests can be found on Github.

Time in image is in milliseconds.