--- /dev/null
+title: Profile Kernel/User Backtraces
+name: pf4.stp
+keywords: profiling
+exit: user-controlled
+description: The pf4.stp script sets up time-based sampling. Every five seconds it prints out a sorted list with the top twenty kernel and/or user stack backtraces (on a per-cpu basis). Use any of --ldd, --all-modules, -d MODULE, -d /PATH/TO/EXEC to add more symbolic info.
+test_check: stap -p4 pf4.stp
+test_installcheck: stap pf4.stp -c "sleep 6" --all-modules --ldd
--- /dev/null
+#! /usr/bin/env stap
+
+global profile%[20000], pcount
+
+probe timer.profile
+ # or perf.type(0).config(0).sample(NNNN) for apprx. every NNNN tsc ticks
+{
+ # add filtering as required:
+ # if (execname() != "program") next
+ # if (uid() != 4345) next
+ # if (! user_mode()) next
+ if (target() && pid() != target()) next # be sensitive to -x PID or -c CMD
+
+ # NB: we count total hits also, because the report only shows top few
+ pcount <<< 1
+
+ bt = user_mode() ? sprint_ubacktrace() : sprint_backtrace()
+ profile[cpu(),bt] <<< 1
+}
+
+probe end,error,timer.ms(5000) {
+ printf ("\n--- %d samples recorded:\n", @count(pcount))
+
+ foreach ([c,b] in profile- limit 20) {
+ printf ("%d hits on cpu %d\n%s\n\n", @count(profile[c,b]), c, b)
+ }
+
+ delete profile
+ delete pcount
+}