post-process ftrace stacktraces to allow using as input for flamegraph

stackcollapse-ftrace.py

#!/usr/bin/env python3
import sys
import collections

def convert_stack(stack):
    return ";".join(stack[::-1])

def process_file(file):
    current_stack = []
    for line in file:
        if '=>' in line:
            function = line.strip().lstrip('=> ')
            current_stack += [function]
        elif current_stack:
            yield convert_stack(current_stack)
            current_stack = []

    if current_stack:
        yield convert_stack(current_stack)

if __name__ == '__main__':
    stacks = collections.defaultdict(int)
    for stack in process_file(sys.stdin):
        stacks[stack] += 1
    for stack, count in stacks.items():
        print(stack, count)