#!/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 #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 (bpf_probe_read(bp, sizeof(*bp), (void *)*bp)) *bp = 0; if (ret < __START_KERNEL_map) return 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); if (val) { (*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="") print(b.ksym(addr, show_offset=offset)) # 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()