toggle for root/leaf merge

[brendangregg]

Current flame graphs merge from root to leaf. It can sometimes be helpful to flip the merge direction, and merge from leaf to root. For example, imagine hundreds of code paths ending in mutex_lock, and trying to gauge the total time in mutex_lock. (Ok, search #2, should help in that specific case).

A means to toggle root/leaf merge would be great. I'm not sure how that's best visualized: probably flipping to an icicle plot for leaf merge, as a visual clue that it is a different flame graph type.

[spiermar]

FlameGraph> cat example-stacks.txt | ./stackcollapse.pl | ./flamegraph.pl --reverse --inverted --title "Leaf Merge" > example-leafmerge.svg

[ceeaspb]

this would be very useful