Hi, I was looking into varnishtop to find performance bottlenecks on a website. Thinking about it I think a useful feature is currently missing from this tool. (while it _has_ all the available raw data). I'd like to discuss it here, to get your opinion.
Currently varnishtop shows the top urls purely based on frequency. Depending on your usecase that might be usefull, but might also NOT give you the bottlenecks you are looking for. I'd like to use varnish for the following (example) scenario: Consider an website site with many dynamic urls. (dynamic means varnish does not cache them, they are always passed through to the backend) Of those there are two urls that are behaving "badly" X and Y (that is they are slow: lets say 400ms) We don't know that _these_ to are behaving badly. X: is called very low frequently -> so this is NOT a perf bottleneck. Y: is called often -> THIS IS THE BOTTLENECK -> this is the url that brings down the site. Z: is called often -> this one is fast -> not a bottleneck. I'd like varnishtop to show Y, (and not X-like urls( urls that are not called often), and not Z-like urls (urls that are fast). For this to work varnishtop should (optionally ofcourse) order the url not by request/rate, but rather by "total time spend" on this url. Something like the product of freq and avg time on an url. in this case expensive url != often called backend url expensive url != slow backend url expensive url = backend url with high total time spend (freq x duration) (So the slow ones, that are called often) What do you guys think ? This would instantly give the problem areas of a website, no ? Regards, Harm Verhagen
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