Possible problem with perf tool

[Kevin Winchester <kjwinchester@gmail.com>]

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