+ Dave Long
On Tue, Dec 4, 2012 at 3:37 AM, Peng Fan xfan87@gmail.com wrote:
hardware platform :* Pandaboard ES Rev B1.* Processor: *Omap4460*. software Version :* linaro-12.10*
kernel config: android_omap4_defconfig. I changed a few options in order to use perf.
*CONFIG_HAVE_PERF_EVENTS=y CONFIG_PERF_EVENTS=y CONFIG_PERF_COUNTERS=y CONFIG_HW_PERF_EVENTS=y*
The command `Perf stat echo "linaro"` gives such results. root@android:/ # perf stat echo "linaro" linaro
Performance counter stats for 'echo linaro':
269.561767 task-clock # 0.148 CPUsutilized 10 context-switches # 0.000 M/sec 1 CPU-migrations # 0.000 M/sec 105 page-faults # 0.000 M/sec 29678044 cycles # 0.110 GHz 0 stalled-cycles-frontend # 0.00% frontend cycles idle 0 stalled-cycles-backend # 0.00% backend cycles idle 0 instructions # 0.00 insns per cycle 0 branches # 0.000 M/sec 0 branch-misses # 0.00% of all branches
1.823486284 seconds time elapsedI use the option `-v`, and I can see that the first number of branches, instructions branch-misses and so on is zero.why?
root@android:/ # perf stat -v echo "linaro" linaro task-clock: 93902590 93902590 93902590 context-switches: 9 93902590 93902590 CPU-migrations: 0 93902590 93902590 page-faults: 104 93902590 93902590 cycles: 4284725 76202392 76202392 stalled-cycles-frontend: 0 76202392 76202392 stalled-cycles-backend: 0 76202392 76202392 instructions: 0 76202392 76202392 branches: 0 76202392 76202392 branch-misses: 0 76202392 76202392
Performance counter stats for 'echo linaro':
93.902590 task-clock # 0.282 CPUsutilized 9 context-switches # 0.000 M/sec 0 CPU-migrations # 0.000 M/sec 104 page-faults # 0.001 M/sec 4284725 cycles # 0.046 GHz
0 stalled-cycles-frontend # 0.00% frontend cyclesidle 0 stalled-cycles-backend # 0.00% backend cycles idle 0 instructions # 0.00 insns per cycle 0 branches # 0.000 M/sec 0 branch-misses # 0.00% of all branches
0.332550049 seconds time elapsedCan anybody give me suggestions?How can I use perf to get the value of hardware performance counter
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