Calculating Service Level Indicator (SLI) for Home Page Request Latency

C.

The Google-recommended way of calculating a Service Level Indicator (SLI) to represent home page request latency with an acceptable page load time set to 100 ms is option C: "Count the number of home page requests that load in under 100 ms, and then divide by the total number of home page requests."

Option A is incorrect because computing the percentile at 100 ms is not equivalent to setting an acceptable page load time of 100 ms. Percentiles are used to understand the distribution of request latencies and to identify the latency that a certain percentage of requests fall under.

Option B is also incorrect because while computing the median and 90th percentiles can provide valuable insights into request latencies, it does not specifically address the question of whether the home page is loading within an acceptable time frame of 100 ms.

Option D is incorrect because it includes all web application requests in the denominator, not just the home page requests. This can dilute the impact of slower requests for other pages on the overall SLI for the home page.

Counting the number of home page requests that load in under 100 ms and dividing by the total number of home page requests gives a percentage that represents the SLI. This SLI indicates what percentage of home page requests are meeting the acceptable page load time of 100 ms. This is a simple and effective way to measure the performance of the home page specifically and to identify areas for improvement.