offwaketime.py for older kernels

tools/old/offwaketime.py

@@ -0,0 +1,284 @@
+#!/usr/bin/python
+#
+# offwaketime Summarize blocked time by kernel off-CPU stack + waker stack
+# For Linux, uses BCC, eBPF.
+#
+# USAGE: offwaketime [-h] [-u] [-p PID] [-T] [duration]
+#
+# 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.
+#
+# The Off-CPU stack is currently limited to a stack trace depth of 20
+# (maxtdepth), and the waker stack limited to 10 (maxwdepth). This is also
+# limited to kernel stacks, and x86_64 only. Check for future versions, where
+# these limitations should be removed.
+#
+# Copyright 2016 Netflix, Inc.
+# Licensed under the Apache License, Version 2.0 (the "License")
+#
+# 20-Jan-2016 Brendan Gregg Created this.
+
+from __future__ import print_function
+from bcc import BPF
+from time import sleep
+import argparse
+import signal
+
+# arguments
+examples = """examples:
+ ./offwaketime # trace off-CPU + waker stack time until Ctrl-C
+ ./offwaketime 5 # trace for 5 seconds only
+ ./offwaketime -f 5 # 5 seconds, and output in folded format
+ ./offwaketime -u # don't include kernel threads (user only)
+ ./offwaketime -p 185 # trace fo PID 185 only
+"""
+parser = argparse.ArgumentParser(
+ description="Summarize blocked time by kernel stack trace + waker stack",
+ formatter_class=argparse.RawDescriptionHelpFormatter,
+ epilog=examples)
+parser.add_argument("-u", "--useronly", action="store_true",
+ help="user threads only (no kernel threads)")
+parser.add_argument("-p", "--pid",
+ help="trace this PID only")
+parser.add_argument("-v", "--verbose", action="store_true",
+ help="show raw addresses")
+parser.add_argument("-f", "--folded", action="store_true",
+ help="output folded format")
+parser.add_argument("duration", nargs="?", default=99999999,
+ help="duration of trace, in seconds")
+args = parser.parse_args()
+folded = args.folded
+duration = int(args.duration)
+debug = 0
+maxwdepth = 10 # and MAXWDEPTH
+maxtdepth = 20 # and MAXTDEPTH
+if args.pid and args.useronly:
+ print("ERROR: use either -p or -u.")
+ exit()
+
+# signal handler
+def signal_ignore(signal, frame):
+ print()
+
+# define BPF program
+bpf_text = """
+#include <uapi/linux/ptrace.h>
+#include <linux/sched.h>
+
+#define MAXWDEPTH 10
+#define MAXTDEPTH 20
+#define MINBLOCK_US 1
+
+struct key_t {
+ char waker[TASK_COMM_LEN];
+ char target[TASK_COMM_LEN];
+ u64 wret[MAXWDEPTH];
+ u64 tret[MAXTDEPTH];
+};
+BPF_HASH(counts, struct key_t);
+BPF_HASH(start, u32);
+struct wokeby_t {
+ char name[TASK_COMM_LEN];
+ u64 ret[MAXWDEPTH];
+};
+BPF_HASH(wokeby, u32, struct wokeby_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 waker(struct pt_regs *ctx, struct task_struct *p) {
+ u32 pid = p->pid;
+
+ if (!(FILTER))
+ return 0;
+
+ u64 bp = 0;
+ struct wokeby_t woke = {};
+ int depth = 0;
+ bpf_get_current_comm(&woke.name, sizeof(woke.name));
+ bp = ctx->bp;
+
+ // unrolled loop (MAXWDEPTH):
+ if (!(woke.ret[depth++] = get_frame(&bp))) goto out;
+ if (!(woke.ret[depth++] = get_frame(&bp))) goto out;
+ if (!(woke.ret[depth++] = get_frame(&bp))) goto out;
+ if (!(woke.ret[depth++] = get_frame(&bp))) goto out;
+ if (!(woke.ret[depth++] = get_frame(&bp))) goto out;
+ if (!(woke.ret[depth++] = get_frame(&bp))) goto out;
+ if (!(woke.ret[depth++] = get_frame(&bp))) goto out;
+ if (!(woke.ret[depth++] = get_frame(&bp))) goto out;
+ if (!(woke.ret[depth++] = get_frame(&bp))) goto out;
+ woke.ret[depth] = get_frame(&bp);
+
+out:
+ wokeby.update(&pid, &woke);
+ return 0;
+}
+
+int oncpu(struct pt_regs *ctx, struct task_struct *p) {
+ u32 pid = p->pid;
+ u64 ts, *tsp;
+
+ // record previous thread sleep time
+ if (FILTER) {
+ ts = bpf_ktime_get_ns();
+ start.update(&pid, &ts);
+ }
+
+ // calculate current thread's delta time
+ pid = bpf_get_current_pid_tgid();
+ tsp = start.lookup(&pid);
+ if (tsp == 0)
+ return 0; // missed start or filtered
+ u64 delta = bpf_ktime_get_ns() - *tsp;
+ start.delete(&pid);
+ delta = delta / 1000;
+ if (delta < MINBLOCK_US)
+ return 0;
+
+ // create map key
+ u64 zero = 0, *val, bp = 0;
+ int depth = 0;
+ struct key_t key = {};
+ struct wokeby_t *woke;
+ bpf_get_current_comm(&key.target, sizeof(key.target));
+ bp = ctx->bp;
+
+ // unrolled loop (MAXTDEPTH):
+ if (!(key.tret[depth++] = get_frame(&bp))) goto out;
+ if (!(key.tret[depth++] = get_frame(&bp))) goto out;
+ if (!(key.tret[depth++] = get_frame(&bp))) goto out;
+ if (!(key.tret[depth++] = get_frame(&bp))) goto out;
+ if (!(key.tret[depth++] = get_frame(&bp))) goto out;
+ if (!(key.tret[depth++] = get_frame(&bp))) goto out;
+ if (!(key.tret[depth++] = get_frame(&bp))) goto out;
+ if (!(key.tret[depth++] = get_frame(&bp))) goto out;
+ if (!(key.tret[depth++] = get_frame(&bp))) goto out;
+ if (!(key.tret[depth++] = get_frame(&bp))) goto out;
+
+ if (!(key.tret[depth++] = get_frame(&bp))) goto out;
+ if (!(key.tret[depth++] = get_frame(&bp))) goto out;
+ if (!(key.tret[depth++] = get_frame(&bp))) goto out;
+ if (!(key.tret[depth++] = get_frame(&bp))) goto out;
+ if (!(key.tret[depth++] = get_frame(&bp))) goto out;
+ if (!(key.tret[depth++] = get_frame(&bp))) goto out;
+ if (!(key.tret[depth++] = get_frame(&bp))) goto out;
+ if (!(key.tret[depth++] = get_frame(&bp))) goto out;
+ if (!(key.tret[depth++] = get_frame(&bp))) goto out;
+ key.tret[depth] = get_frame(&bp);
+
+out:
+ woke = wokeby.lookup(&pid);
+ if (woke) {
+ __builtin_memcpy(&key.wret, woke->ret, sizeof(key.wret));
+ __builtin_memcpy(&key.waker, woke->name, TASK_COMM_LEN);
+ wokeby.delete(&pid);
+ }
+
+ val = counts.lookup_or_init(&key, &zero);
+ (*val) += delta;
+ return 0;
+}
+"""
+if args.pid:
+ filter = 'pid == %s' % args.pid
+elif args.useronly:
+ filter = '!(p->flags & PF_KTHREAD)'
+else:
+ filter = '1'
+bpf_text = bpf_text.replace('FILTER', filter)
+if debug:
+ print(bpf_text)
+
+# initialize BPF
+b = BPF(text=bpf_text)
+b.attach_kprobe(event="finish_task_switch", fn_name="oncpu")
+b.attach_kprobe(event="try_to_wake_up", fn_name="waker")
+matched = b.num_open_kprobes()
+if matched == 0:
+ print("0 functions traced. Exiting.")
+ exit()
+
+# header
+if not folded:
+ print("Tracing blocked time (us) by kernel off-CPU and waker stack",
+ end="")
+ if duration < 99999999:
+ print(" for %d secs." % duration)
+ else:
+ print("... Hit Ctrl-C to end.")
+
+# output
+while (1):
+ try:
+ sleep(duration)
+ except KeyboardInterrupt:
+ # as cleanup can take many seconds, trap Ctrl-C:
+ signal.signal(signal.SIGINT, signal_ignore)
+
+ if not folded:
+ print()
+ counts = b.get_table("counts")
+ for k, v in sorted(counts.items(), key=lambda counts: counts[1].value):
+ if folded:
+ # fold target stack
+ line = k.target + ";"
+ for i in reversed(range(0, maxtdepth)):
+ if k.tret[i] == 0:
+ continue
+ line = line + b.ksym(k.tret[i])
+ if i != 0:
+ line = line + ";"
+
+ # add delimiter
+ line = line + ";-"
+
+ # fold waker stack
+ for i in range(0, maxwdepth):
+ line = line + ";"
+ if k.wret[i] == 0:
+ break
+ line = line + b.ksym(k.wret[i])
+ if i != 0:
+ line = line + ";" + k.waker
+
+ # print as a line
+ print("%s %d" % (line, v.value))
+ else:
+ # print wakeup name then stack in reverse order
+ print(" %-16s %s" % ("waker:", k.waker))
+ for i in reversed(range(0, maxwdepth)):
+ if k.wret[i] == 0:
+ continue
+ print(" %-16x %s" % (k.wret[i],
+ b.ksym(k.wret[i])))
+
+ # print delimiter
+ print(" %-16s %s" % ("-", "-"))
+
+ # print default multi-line stack output
+ for i in range(0, maxtdepth):
+ if k.tret[i] == 0:
+ break
+ print(" %-16x %s" % (k.tret[i],
+ b.ksym(k.tret[i])))
+ print(" %-16s %s" % ("target:", k.target))
+ print(" %d\n" % v.value)
+ counts.clear()
+
+ if not folded:
+ print("Detaching...")
+ exit()