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#! /usr/bin/python3 # @lint-avoid-python-3-compatibility-imports # # funcslower Trace slow kernel or user function calls. # For Linux, uses BCC, eBPF. # # USAGE: funcslower [-h] [-p PID] [-m MIN_MS] [-u MIN_US] [-a ARGUMENTS] # [-T] [-t] [-v] function [function ...] # # WARNING: This tool traces function calls by instrumenting the entry and # return from each function. For commonly-invoked functions like memory allocs # or file writes, this can be extremely expensive. Mind the overhead. # # NOTE: This tool cannot trace nested functions in the same invocation # due to instrumentation specifics, only innermost calls will be visible. # # By default, a minimum millisecond threshold of 1 is used. # # Copyright 2017, Sasha Goldshtein # Licensed under the Apache License, Version 2.0 (the "License") # # 30-Mar-2017 Sasha Goldshtein Created this. from __future__ import print_function from bcc import BPF import argparse import time examples = """examples: ./funcslower vfs_write # trace vfs_write calls slower than 1ms ./funcslower -m 10 vfs_write # same, but slower than 10ms ./funcslower -u 10 c:open # trace open calls slower than 10us ./funcslower -p 135 c:open # trace pid 135 only ./funcslower c:malloc c:free # trace both malloc and free slower than 1ms ./funcslower -a 2 c:open # show first two arguments to open ./funcslower -UK -m 10 c:open # Show user and kernel stack frame of open calls slower than 10ms ./funcslower -f -UK c:open # Output in folded format for flame graphs """ parser = argparse.ArgumentParser( description="Trace slow kernel or user function calls.", formatter_class=argparse.RawDescriptionHelpFormatter, epilog=examples) parser.add_argument("-p", "--pid", type=int, metavar="PID", dest="tgid", help="trace this PID only") parser.add_argument("-m", "--min-ms", type=float, dest="min_ms", help="minimum duration to trace (ms)") parser.add_argument("-u", "--min-us", type=float, dest="min_us", help="minimum duration to trace (us)") parser.add_argument("-a", "--arguments", type=int, help="print this many entry arguments, as hex") parser.add_argument("-T", "--time", action="store_true", help="show HH:MM:SS timestamp") parser.add_argument("-t", "--timestamp", action="store_true", help="show timestamp in seconds at us resolution") parser.add_argument("-v", "--verbose", action="store_true", help="print the BPF program for debugging purposes") parser.add_argument(metavar="function", nargs="+", dest="functions", help="function(s) to trace") parser.add_argument("--ebpf", action="store_true", help=argparse.SUPPRESS) parser.add_argument("-f", "--folded", action="store_true", help="output folded format, one line per stack (for flame graphs)") parser.add_argument("-U", "--user-stack", action="store_true", help="output user stack trace") parser.add_argument("-K", "--kernel-stack", action="store_true", help="output kernel stack trace") args = parser.parse_args() # fractions are allowed, but rounded to an integer nanosecond if args.min_ms: duration_ns = int(args.min_ms * 1000000) elif args.min_us: duration_ns = int(args.min_us * 1000) else: duration_ns = 1000000 # default to 1ms bpf_text = """ #include <uapi/linux/ptrace.h> #include <linux/sched.h> // for TASK_COMM_LEN struct entry_t { u64 id; u64 start_ns; #ifdef GRAB_ARGS #ifndef __s390x__ u64 args[6]; #else u64 args[5]; #endif #endif #ifdef USER_STACKS int user_stack_id; #endif #ifdef KERNEL_STACKS int kernel_stack_id; u64 kernel_ip; #endif }; struct data_t { u64 id; u64 tgid_pid; u64 start_ns; u64 duration_ns; u64 retval; char comm[TASK_COMM_LEN]; #ifdef GRAB_ARGS #ifndef __s390x__ u64 args[6]; #else u64 args[5]; #endif #endif #ifdef USER_STACKS int user_stack_id; #endif #ifdef KERNEL_STACKS int kernel_stack_id; u64 kernel_ip; #endif }; BPF_HASH(entryinfo, u64, struct entry_t); BPF_PERF_OUTPUT(events); #if defined(USER_STACKS) || defined(KERNEL_STACKS) BPF_STACK_TRACE(stacks, 2048); #endif static int trace_entry(struct pt_regs *ctx, int id) { u64 tgid_pid = bpf_get_current_pid_tgid(); u32 tgid = tgid_pid >> 32; if (TGID_FILTER) return 0; u32 pid = tgid_pid; struct entry_t entry = {}; entry.start_ns = bpf_ktime_get_ns(); entry.id = id; #ifdef GRAB_ARGS entry.args[0] = PT_REGS_PARM1(ctx); entry.args[1] = PT_REGS_PARM2(ctx); entry.args[2] = PT_REGS_PARM3(ctx); entry.args[3] = PT_REGS_PARM4(ctx); entry.args[4] = PT_REGS_PARM5(ctx); #ifndef __s390x__ entry.args[5] = PT_REGS_PARM6(ctx); #endif #endif #ifdef USER_STACKS entry.user_stack_id = stacks.get_stackid(ctx, BPF_F_USER_STACK); #endif #ifdef KERNEL_STACKS entry.kernel_stack_id = stacks.get_stackid(ctx, 0); if (entry.kernel_stack_id >= 0) { u64 ip = PT_REGS_IP(ctx); u64 page_offset; // if ip isn't sane, leave key ips as zero for later checking #if defined(CONFIG_X86_64) && defined(__PAGE_OFFSET_BASE) // x64, 4.16, ..., 4.11, etc., but some earlier kernel didn't have it page_offset = __PAGE_OFFSET_BASE; #elif defined(CONFIG_X86_64) && defined(__PAGE_OFFSET_BASE_L4) // x64, 4.17, and later #if defined(CONFIG_DYNAMIC_MEMORY_LAYOUT) && defined(CONFIG_X86_5LEVEL) page_offset = __PAGE_OFFSET_BASE_L5; #else page_offset = __PAGE_OFFSET_BASE_L4; #endif #else // earlier x86_64 kernels, e.g., 4.6, comes here // arm64, s390, powerpc, x86_32 page_offset = PAGE_OFFSET; #endif if (ip > page_offset) { entry.kernel_ip = ip; } } #endif entryinfo.update(&tgid_pid, &entry); return 0; } int trace_return(struct pt_regs *ctx) { struct entry_t *entryp; u64 tgid_pid = bpf_get_current_pid_tgid(); entryp = entryinfo.lookup(&tgid_pid); if (entryp == 0) { return 0; } u64 delta_ns = bpf_ktime_get_ns() - entryp->start_ns; entryinfo.delete(&tgid_pid); if (delta_ns < DURATION_NS) return 0; struct data_t data = {}; data.id = entryp->id; data.tgid_pid = tgid_pid; data.start_ns = entryp->start_ns; data.duration_ns = delta_ns; data.retval = PT_REGS_RC(ctx); #ifdef USER_STACKS data.user_stack_id = entryp->user_stack_id; #endif #ifdef KERNEL_STACKS data.kernel_stack_id = entryp->kernel_stack_id; data.kernel_ip = entryp->kernel_ip; #endif #ifdef GRAB_ARGS bpf_probe_read_kernel(&data.args[0], sizeof(data.args), entryp->args); #endif bpf_get_current_comm(&data.comm, sizeof(data.comm)); events.perf_submit(ctx, &data, sizeof(data)); return 0; } """ bpf_text = bpf_text.replace('DURATION_NS', str(duration_ns)) if args.arguments: bpf_text = "#define GRAB_ARGS\n" + bpf_text if args.user_stack: bpf_text = "#define USER_STACKS\n" + bpf_text if args.kernel_stack: bpf_text = "#define KERNEL_STACKS\n" + bpf_text if args.tgid: bpf_text = bpf_text.replace('TGID_FILTER', 'tgid != %d' % args.tgid) else: bpf_text = bpf_text.replace('TGID_FILTER', '0') for i in range(len(args.functions)): bpf_text += """ int trace_%d(struct pt_regs *ctx) { return trace_entry(ctx, %d); } """ % (i, i) if args.verbose or args.ebpf: print(bpf_text) if args.ebpf: exit() b = BPF(text=bpf_text) for i, function in enumerate(args.functions): if ":" in function: library, func = function.split(":") b.attach_uprobe(name=library, sym=func, fn_name="trace_%d" % i) b.attach_uretprobe(name=library, sym=func, fn_name="trace_return") else: b.attach_kprobe(event=function, fn_name="trace_%d" % i) b.attach_kretprobe(event=function, fn_name="trace_return") time_designator = "us" if args.min_us else "ms" time_value = args.min_us or args.min_ms or 1 time_multiplier = 1000 if args.min_us else 1000000 time_col = args.time or args.timestamp # Do not print header when folded if not args.folded: print("Tracing function calls slower than %g %s... Ctrl+C to quit." % (time_value, time_designator)) print((("%-10s " % "TIME" if time_col else "") + "%-14s %-6s %7s %16s %s") % ("COMM", "PID", "LAT(%s)" % time_designator, "RVAL", "FUNC" + (" ARGS" if args.arguments else ""))) earliest_ts = 0 def time_str(event): if args.time: return "%-10s " % time.strftime("%H:%M:%S") if args.timestamp: global earliest_ts if earliest_ts == 0: earliest_ts = event.start_ns return "%-10.6f " % ((event.start_ns - earliest_ts) / 1000000000.0) return "" def args_str(event): if not args.arguments: return "" return str.join(" ", ["0x%x" % arg for arg in event.args[:args.arguments]]) def print_stack(event): user_stack = [] stack_traces = b.get_table("stacks") if args.user_stack and event.user_stack_id > 0: user_stack = stack_traces.walk(event.user_stack_id) kernel_stack = [] if args.kernel_stack and event.kernel_stack_id > 0: kernel_tmp = stack_traces.walk(event.kernel_stack_id) # fix kernel stack for addr in kernel_tmp: kernel_stack.append(addr) do_delimiter = user_stack and kernel_stack if args.folded: # print folded stack output user_stack = list(user_stack) kernel_stack = list(kernel_stack) line = [event.comm] + \ [b.sym(addr, event.tgid_pid) for addr in reversed(user_stack)] + \ (do_delimiter and ["-"] or []) + \ [b.ksym(addr) for addr in reversed(kernel_stack)] print("%s %d" % (b';'.join(line).decode('utf-8', 'replace'), 1)) else: # print default multi-line stack output. for addr in kernel_stack: print(" %s" % b.ksym(addr).decode('utf-8', 'replace')) for addr in user_stack: print(" %s" % b.sym(addr, event.tgid_pid).decode('utf-8', 'replace')) def print_event(cpu, data, size): event = b["events"].event(data) ts = float(event.duration_ns) / time_multiplier if not args.folded: print((time_str(event) + "%-14.14s %-6s %7.2f %16x %s %s") % (event.comm.decode('utf-8', 'replace'), event.tgid_pid >> 32, ts, event.retval, args.functions[event.id], args_str(event))) if args.user_stack or args.kernel_stack: print_stack(event) b["events"].open_perf_buffer(print_event, page_cnt=64) while True: try: b.perf_buffer_poll() except KeyboardInterrupt: exit()