Possible problem with perf tool

From: Kevin Winchester
Date: Wed Jul 01 2009 - 20:04:10 EST



I was playing with perf to get an idea of what it can do, so I started with a basic test:

$ perf stat ls
CREDITS PERF-BUILD-OPTIONS builtin-annotate.c builtin-help.o builtin-record.c builtin-report.o builtin-top.c command-list.txt libperf.a perf.h
Documentation PERF-CFLAGS builtin-annotate.o builtin-list.c builtin-record.o builtin-stat.c builtin-top.o common-cmds.h perf perf.o
Makefile PERF-VERSION-FILE builtin-help.c builtin-list.o builtin-report.c builtin-stat.o builtin.h design.txt perf.c util

Performance counter stats for 'ls':

1.675774 task-clock-msecs # 0.772 CPUs
13 context-switches # 0.008 M/sec
0 CPU-migrations # 0.000 M/sec
212 page-faults # 0.127 M/sec
2925124 cycles # 1745.536 M/sec
1048640 instructions # 0.358 IPC
547552 cache-references # 326.746 M/sec
8455 cache-misses # 5.045 M/sec

0.002170123 seconds time elapsed




Looks good, so I tried:

$ perf stat ls -l
Error: unknown switch `l'




So I tried instead:

$ perf stat 'ls -l'
ls -l: No such file or directory

Performance counter stats for 'ls -l':

<not counted> task-clock-msecs
<not counted> context-switches
<not counted> CPU-migrations
<not counted> page-faults
<not counted> cycles
<not counted> instructions
<not counted> cache-references
<not counted> cache-misses

0.000594919 seconds time elapsed





Am I doing something wrong here? Or perhaps perf should be taught the difference between command-line switches before or after the perf command (e.g. stat) being invoked?

--
Kevin Winchester


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