stack walking scripts
diff --git a/tools/stackcount b/tools/stackcount
new file mode 100755
index 0000000..b6cc3b6
--- /dev/null
+++ b/tools/stackcount
@@ -0,0 +1,179 @@
+#!/usr/bin/python
+#
+# stackcount Count kernel function calls and their stack traces.
+# For Linux, uses BCC, eBPF.
+#
+# USAGE: stackcount [-h] [-p PID] [-i INTERVAL] [-T] [-r] pattern
+#
+# The pattern is a string with optional '*' wildcards, similar to file
+# globbing. If you'd prefer to use regular expressions, use the -r option.
+#
+# The current implementation uses an unrolled loop for x86_64, and was written
+# as a proof of concept. This implementation should be replaced in the future
+# with an appropriate bpf_ call, when available.
+#
+# Currently limited to a stack trace depth of 11 (maxdepth + 1).
+#
+# Copyright 2016 Netflix, Inc.
+# Licensed under the Apache License, Version 2.0 (the "License")
+#
+# 12-Jan-2016 Brendan Gregg Created this.
+
+from __future__ import print_function
+from bcc import BPF
+from time import sleep, strftime
+import argparse
+import signal
+
+# arguments
+examples = """examples:
+ ./stackcount submit_bio # count kernel stack traces for submit_bio
+ ./stackcount ip_output # count kernel stack traces for ip_output
+ ./stackcount -s ip_output # show symbol offsets
+ ./stackcount -sv ip_output # show offsets and raw addresses (verbose)
+ ./stackcount 'tcp_send*' # count stacks for funcs matching tcp_send*
+ ./stackcount -r '^tcp_send.*' # same as above, using regular expressions
+ ./stackcount -Ti 5 ip_output # output every 5 seconds, with timestamps
+ ./stackcount -p 185 ip_output # count ip_output stacks for PID 185 only
+"""
+parser = argparse.ArgumentParser(
+ description="Count kernel function calls and their stack traces",
+ formatter_class=argparse.RawDescriptionHelpFormatter,
+ epilog=examples)
+parser.add_argument("-p", "--pid",
+ help="trace this PID only")
+parser.add_argument("-i", "--interval", default=99999999,
+ help="summary interval, seconds")
+parser.add_argument("-T", "--timestamp", action="store_true",
+ help="include timestamp on output")
+parser.add_argument("-r", "--regexp", action="store_true",
+ help="use regular expressions. Default is \"*\" wildcards only.")
+parser.add_argument("-s", "--offset", action="store_true",
+ help="show address offsets")
+parser.add_argument("-v", "--verbose", action="store_true",
+ help="show raw addresses")
+parser.add_argument("pattern",
+ help="search expression for kernel functions")
+args = parser.parse_args()
+pattern = args.pattern
+if not args.regexp:
+ pattern = pattern.replace('*', '.*')
+ pattern = '^' + pattern + '$'
+offset = args.offset
+verbose = args.verbose
+debug = 0
+maxdepth = 10 # and MAXDEPTH
+
+# signal handler
+def signal_ignore(signal, frame):
+ print()
+
+# load BPF program
+bpf_text = """
+#include <uapi/linux/ptrace.h>
+
+#define MAXDEPTH 10
+
+struct key_t {
+ u64 ip;
+ u64 ret[MAXDEPTH];
+};
+BPF_HASH(counts, struct key_t);
+
+static u64 get_frame(u64 *bp) {
+ if (*bp) {
+ // The following stack walker is x86_64 specific
+ u64 ret = 0;
+ if (bpf_probe_read(&ret, sizeof(ret), (void *)(*bp+8)))
+ return 0;
+ if (!ret || ret < __START_KERNEL_map)
+ return 0;
+ if (bpf_probe_read(bp, sizeof(*bp), (void *)*bp))
+ bp = 0;
+ return ret;
+ }
+ return 0;
+}
+
+int trace_count(struct pt_regs *ctx) {
+ FILTER
+ struct key_t key = {};
+ u64 zero = 0, *val, bp = 0;
+ int depth = 0;
+
+ key.ip = ctx->ip;
+ bp = ctx->bp;
+
+ // unrolled loop, 10 (MAXDEPTH) frames deep:
+ if (!(key.ret[depth++] = get_frame(&bp))) goto out;
+ if (!(key.ret[depth++] = get_frame(&bp))) goto out;
+ if (!(key.ret[depth++] = get_frame(&bp))) goto out;
+ if (!(key.ret[depth++] = get_frame(&bp))) goto out;
+ if (!(key.ret[depth++] = get_frame(&bp))) goto out;
+ if (!(key.ret[depth++] = get_frame(&bp))) goto out;
+ if (!(key.ret[depth++] = get_frame(&bp))) goto out;
+ if (!(key.ret[depth++] = get_frame(&bp))) goto out;
+ if (!(key.ret[depth++] = get_frame(&bp))) goto out;
+ if (!(key.ret[depth++] = get_frame(&bp))) goto out;
+
+out:
+ val = counts.lookup_or_init(&key, &zero);
+ (*val)++;
+ return 0;
+}
+"""
+if args.pid:
+ bpf_text = bpf_text.replace('FILTER',
+ ('u32 pid; pid = bpf_get_current_pid_tgid(); ' +
+ 'if (pid != %s) { return 0; }') % (args.pid))
+else:
+ bpf_text = bpf_text.replace('FILTER', '')
+if debug:
+ print(bpf_text)
+b = BPF(text=bpf_text)
+b.attach_kprobe(event_re=pattern, fn_name="trace_count")
+matched = b.num_open_kprobes()
+if matched == 0:
+ print("0 functions matched by \"%s\". Exiting." % args.pattern)
+ exit()
+
+# header
+print("Tracing %d functions for \"%s\"... Hit Ctrl-C to end." %
+ (matched, args.pattern))
+
+def print_frame(addr):
+ print(" ", end="")
+ if verbose:
+ print("%-16x " % addr, end="")
+ if offset:
+ print("%s" % b.ksymaddr(addr))
+ else:
+ print("%s" % b.ksym(addr))
+
+# output
+exiting = 0 if args.interval else 1
+while (1):
+ try:
+ sleep(int(args.interval))
+ except KeyboardInterrupt:
+ exiting = 1
+ # as cleanup can take many seconds, trap Ctrl-C:
+ signal.signal(signal.SIGINT, signal_ignore)
+
+ print()
+ if args.timestamp:
+ print("%-8s\n" % strftime("%H:%M:%S"), end="")
+
+ counts = b.get_table("counts")
+ for k, v in sorted(counts.items(), key=lambda counts: counts[1].value):
+ print_frame(k.ip)
+ for i in range(0, maxdepth):
+ if k.ret[i] == 0:
+ break
+ print_frame(k.ret[i])
+ print(" %d\n" % v.value)
+ counts.clear()
+
+ if exiting:
+ print("Detaching...")
+ exit()