#!/usr/bin/env bcc-lua
|
--[[
|
Copyright 2016 Marek Vavrusa <mvavrusa@cloudflare.com>
|
|
Licensed under the Apache License, Version 2.0 (the "License");
|
you may not use this file except in compliance with the License.
|
You may obtain a copy of the License at
|
|
http://www.apache.org/licenses/LICENSE-2.0
|
|
Unless required by applicable law or agreed to in writing, software
|
distributed under the License is distributed on an "AS IS" BASIS,
|
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
See the License for the specific language governing permissions and
|
limitations under the License.
|
]]
|
-- Summarize off-CPU time by stack trace
|
-- Related tool: https://github.com/iovisor/bcc/blob/master/tools/offcputime.py
|
local ffi = require('ffi')
|
local bpf = require('bpf')
|
local S = require('syscall')
|
-- Create BPF maps
|
-- TODO: made smaller to fit default memory limits
|
local key_t = 'struct { char name[16]; int32_t stack_id; }'
|
local starts = assert(bpf.map('hash', 128, ffi.typeof('uint32_t'), ffi.typeof('uint64_t')))
|
local counts = assert(bpf.map('hash', 128, ffi.typeof(key_t), ffi.typeof('uint64_t')))
|
local stack_traces = assert(bpf.map('stack_trace', 16))
|
-- Open tracepoint and attach BPF program
|
-- The 'arg' parses tracepoint format automatically
|
local tp = bpf.tracepoint('sched/sched_switch', function (arg)
|
-- Update previous thread sleep time
|
local pid = arg.prev_pid
|
local now = time()
|
starts[pid] = now
|
-- Calculate current thread's delta time
|
pid = arg.next_pid
|
local from = starts[pid]
|
if not from then
|
return 0
|
end
|
local delta = (now - from) / 1000
|
starts[pid] = nil
|
-- Check if the delta is below 1us
|
if delta < 1 then
|
return
|
end
|
-- Create key for this thread
|
local key = ffi.new(key_t)
|
comm(key.name)
|
key.stack_id = stack_id(stack_traces, BPF.F_FAST_STACK_CMP)
|
-- Update current thread off cpu time with delta
|
local val = counts[key]
|
if not val then
|
counts[key] = 0
|
end
|
xadd(counts[key], delta)
|
end, 0, -1)
|
-- Helper: load kernel symbols
|
ffi.cdef 'unsigned long long strtoull(const char *, char **, int);'
|
local ksyms = {}
|
for l in io.lines('/proc/kallsyms') do
|
local addr, sym = l:match '(%w+) %w (%S+)'
|
if addr then ksyms[ffi.C.strtoull(addr, nil, 16)] = sym end
|
end
|
-- User-space part of the program
|
while true do
|
for k,v in counts.pairs,counts,nil do
|
local s = ''
|
local traces = stack_traces[k.stack_id]
|
if traces then
|
for i, ip in ipairs(traces) do
|
s = s .. string.format(" %-16p %s", ip, ksyms[ip])
|
end
|
end
|
s = s .. string.format(" %-16s %s", "-", ffi.string(k.name))
|
s = s .. string.format(" %d", tonumber(v))
|
print(s)
|
end
|
S.sleep(1)
|
end
|
