Add stackcollapse-trace-cmd.rb

stackcollapse-trace-cmd.rb

@@ -0,0 +1,51 @@
+#!/usr/bin/ruby
+#
+# Usage:
+#
+#   $ sudo trace-cmd record -p function_graph -l do_linkat
+#   $ sudo trace-cmd report | MIN_LATENCY_US=500 ruby stackcollapse-trace-cmd.rb | flamegraph.pl --hash --colors=perl --flamechart > flamechart.svg
+
+stack = []
+buffer = []
+
+MIN_LATENCY_US = ENV['MIN_LATENCY_US']&.to_i || 1000
+
+STDIN.each_line do |line|
+  # gitaly-3521172 [019] 8001008.806633: funcgraph_entry:                   |  do_linkat() {
+  # gitaly-3521172 [019] 8001008.806634: funcgraph_entry:                   |    filename_lookup() {
+  # gitaly-3521172 [019] 8001008.806634: funcgraph_entry:                   |      path_lookupat.isra.0() {
+  # gitaly-3521172 [019] 8001008.806635: funcgraph_entry:                   |        path_init() {
+  # gitaly-3521172 [019] 8001008.806635: funcgraph_entry:                   |          nd_jump_root() {
+  # gitaly-3521172 [019] 8001008.806636: funcgraph_entry:        0.349 us   |            set_root();
+  # gitaly-3521172 [019] 8001008.806636: funcgraph_exit:         1.170 us   |          }
+  # gitaly-3521172 [019] 8001008.806637: funcgraph_exit:         1.779 us   |        }
+
+  if m = /^\s+\S+\s+\[\d+\]\s+\d+\.\d+:\s+funcgraph_entry:\s+\|\s+(.+)\(\)\s+\{$/.match(line)
+    func = m[1]
+    stack << [func, 0]
+  elsif m = /^\s+\S+\s+\[\d+\]\s+\d+\.\d+:\s+funcgraph_entry:\s+[+!#]?\s(\d+\.\d+) us\s+\|\s+(.+)\(\);$/.match(line)
+    latency = m[1].to_f
+    func = m[2]
+    buffer << "#{(stack.map(&:first) + [func]).join(';')} #{latency}"
+    stack.each do |frame|
+      frame[1] += latency
+    end
+  elsif m = /^\s+\S+\s+\[\d+\]\s+\d+\.\d+:\s+funcgraph_exit:\s+[+!#]?\s(\d+\.\d+) us\s+\|\s+\}$/.match(line)
+    func, latency_consumed = stack.pop
+    latency = m[1].to_f
+    buffer << "#{(stack.map(&:first) + [func]).join(';')} #{(latency - latency_consumed)}"
+
+    stack.each do |frame|
+      frame[1] += (latency - latency_consumed)
+    end
+
+    if stack.size == 0
+      buffer << 'dummy 0'
+      puts buffer if latency > MIN_LATENCY_US
+      buffer = []
+    end
+  elsif m = /^(CPU \d+ is empty|cpus=\d+)$/.match(line)
+  else
+    warn "unknown line: #{line}"
+  end
+end