Ability to compare separate runs

[jokkedk]

As requested by Bharat Mediratta:

"Hey Joakim. Thanks again for webgrind, it is very useful. I'm using it to optimize Gallery3 and one of my most common operations is to make a change and try to predict then demonstrate a performance delta. The way I do it now is that I do a couple of ?XDEBUG_PROFILE runs before and after my change, then open them all up in tabs in Chrome and switch back and forth between the two to compare numbers.

What would help me there would be a way to figure out the delta between two runs so that I could get an idea of the impact of a change. Eg, it would be very nice to know that function foo() took up 10% of my total request processing time before and 7% afterwards.

As a bonus if I could aggregate a set of runs and label them, then compare between labels I could use the aggregation to reduce the noise between multiple runs. Simple aggregation that just took the average would be a fine start although in a perfect world I could do 10 runs and it would drop the outliers.

Not a trivial request, I'm sure. Thanks for your consideration!"

[jokkedk]

Agreed - This is the number 1 feature I could use as well. Just being able to compare the current run with the last would be extremely helpful (something like a little +10% next to the current percentage, or -42ms next to the current time).