See bug 1061759, I'm going to be calling the 3rd column 'Samples' from here on out. If you look at the screenshot, compare the (root) node with DSC_allocId. Notice that (root) has 100% cost but DSC_allocId has 17%. This doesn't seem to add up at all with the call/samples count. Profile from bug 1045715.

The 17% is time, not samples.

What is the 3rd column and why is the 3rd column not equal to the second column multiplied by a constant?

I discussed with victor in person. We added a sample time back in the day to the profiler backend to know when the profiler failed to capture a sample on time. In the screenshot we're using this to compute duration/time but we agreed that this wasn't accurate to report as Cost/Time since really we don't know what occurred during these missed samples and charging that to the site where we finally take the sample is misleading.

Comment on attachment 8491677 [details] [diff] [review] v1 Review of attachment 8491677 [details] [diff] [review]: ----------------------------------------------------------------- Alright, this change makes sense to me. In these kinds of UIs though, it's hard to know what each column mean and how it's calculated, so it's hard for a user to know what to look for when investigating problems. So I think column header tooltips would help here.