---------- Forwarded message ----------
From: Amit Tomer <amittome...@gmail.com>
Date: Wed, Nov 6, 2013 at 7:03 PM
Subject: Perf support for stalled-cycles-frontend and
stalled-cycles-backend event
To: linux-perf-users@vger.kernel.org
Cc: Will Deacon <will.dea...@arm.com>
We recently installed Perf tool on our platform based on Cortex A-15
cores and Linux kerenl 3.4.8.
We enabled the Hardware Performance counter(PMU) and can see below
message in dmeg log .
[ 2.292157] hw perfevents: enabled with ARMv7 Cortex-A15 PMU
driver, 7 counters available
This message suggests there are 7 counter avaiable here.
But when we run the below command ,we find two counters named
stalled-cycles-frontend and stalled-cycles-backend are not suported
#########################################
root@fzm-k2:~# perf stat -v ./helloworld
Warning: stalled-cycles-frontend event is not supported by the kernel.
Warning: stalled-cycles-backend event is not supported by the kernel.
This is helloworld
pRet: 0
pRet: 0
pRet: 0
cg_rc,: 0
pRet: 0
pRet: 0
pRet: 110
pthread timeout done
task-clock: 4510376 4510376 4510376
context-switches: 1 4510376 4510376
cpu-migrations: 0 4510376 4510376
page-faults: 124 4510376 4510376
cycles: 5524151 4516123 4516123
stalled-cycles-frontend: 0 0 0
stalled-cycles-backend: 0 0 0
instructions: 1470222 4516123 4516123
branches: 432570 4516123 4516123
branch-misses: 14388 4516123 4516123
Performance counter stats for './helloworld':
4.510376 task-clock # 0.000 CPUs utilized
1 context-switches # 0.222 K/sec
0 cpu-migrations # 0.000 K/sec
124 page-faults # 0.027 M/sec
5524151 cycles # 1.225 GHz
<not supported> stalled-cycles-frontend
<not supported> stalled-cycles-backend
1470222 instructions # 0.27 insns per cycle
432570 branches # 95.906 M/sec
14388 branch-misses # 3.33% of all branches
60.005505884 seconds time elapsed
Now as we can see that these two counter are not supported here,can
anybody let us know how do we provide support for both them.
Also, why CPU's utilization is showing Zero here??
Thanks
Amit.
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