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|
.:: debugging ::.
--------------------------------------------------------------------------------
#
# strace(1)
#
strace [OPTS] [ELF]
-f .......... follow child processes on fork(2)
-p <pid> .... attach to running process
-s <size> ... max string size (default: 32)
-e <expr> ... expression for trace filtering
-o <file> ... log output into <file>
-c .......... dump syscall statitics at the end
useful <expr>:
trace=syscall[,syscall] .... trace only syscall listed
trace=file ................. trace all syscall that take a filename as arg
trace=process .............. trace process management related syscalls
signal ..................... trace signals delivered to the process
use cases:
- trace 'open & socket' syscalls for a running process + childs
strace -f -p <pid> -e trace=open,socket
- trace signals delivered to a running process
strace -f -p <pid> -e signal
#
# lsof(8)
#
lsof +fg -p <pid>
-p <pid> ... list open files for process
+fg ........ show file flags for file descripros
file flags:
R/W/RW ..... read/write/read-write
CR ......... create
AP ......... append
TR ......... truncate
uase cases:
- show open files with file flags
lsof +fg -p <pid>
#
# pmap(1)
#
pmap <pid>
............. dump virtual memory map of process.
compared to /proc/<pid>/maps it shows the size of the mappings
#
# pstack(1)
#
pstack <pid>
............. dump current stack of process + threads
#
# pidstat(1)
#
# trace minor/major page faults
pidstat -r -p <pid> [interval]
minor_pagefault: happens when the page needed is already in memory but not
allocated to the faulting process, in that case the kernel
only has to create a new page-table entry pointing to the
shared physical page
major_pagefault: happends when the page needed is NOT in memory, the kernel
has to create a new page-table entry and populate the
physical page
#
# /usr/bin/time(1)
#
# statistics of process run
/usr/bin/time -v <cmd>
#
# perf(1)
#
# get supported events
perf list
......... show supported hw/sw events
perf stat
-p <pid> .. show stats for running process
-I <ms> ... show stats periodically over interval <ms>
-e <ev> ... filter for events
perf top
-p <pid> .. show stats for running process
-F <hz> ... sampling frequency
-K ........ hide kernel threads
perf record
-p <pid> ............... record stats for running process
-F <hz> ................ sampling frequency
--call-graph <method> .. [fp, dwarf, lbr] method how to caputre backtrace
fp : use frame-pointer, need -fno-omit-frame-pointer
dwarf: use .cfi debug information
lbr : use hardware last branch record facility
-g ..................... short-hand for --call-graph fp
-e <ev> ................ filter for events
perf report
-n .................... annotate symbols with nr of samples
--stdio ............... report to stdio, if not presen tui mode
-g graph,0.5,caller ... show caller based call chains with value >0.5
useful <ev>:
page-faults
minor-faults
major-faults
cpu-cycles`
task-clock
#
# flamegraph(https://github.com/brendangregg/FlameGraph)
#
# flamegraph for single event trace
perf record -g -p <pid> -e cpu-cycles
perf script | FlameGraph/stackcollapse-perf.pl | FlameGraph/flamegraph.pl > cycles-flamegraph.svg
# flamegraphs for multiple events trace
perf record -g -p <pid> -e cpu-cycles,page-faults
perf script --per-event-dump
# fold & generate as above
#
#
# OProfile
#
operf -g -p <pid>
-g ...... caputre call-graph information
opreport [opt] FILE
NOOPT ... show time spent per binary image
-l ...... show time spent per symbol
-c ...... show callgraph information (see below)
-a ...... add column with time spent accumulated over child nodes
ophelp
NOOPT ... show supported hw/sw events
--------------------------------------------------------------------------------
vim:sts=2:et:tw=80:cc=80:fo+=t:ft=help
|
