am using the Linux Perf tool to monitor certain events for my benchmarking runs. In the event list argument -e, I added cycles-t and cycles-ct since I want to capture them. But both of them always return 0 when I run perf.

I am using following command for example:

perf stat -e cycles-ct dd if=/dev/zero of=/dev/numm count=10000

and this is the output

10000+0 records in
10000+0 records out
5120000 bytes (5.1 MB) copied, 0.0318331 s, 161 MB/s

 Performance counter stats for 'dd if=/dev/zero of=/dev/numm count=10000':

        31,957,327      cycles-ct                
                 0      cpu/cycles-ct/                                              

       0.035254063 seconds time elapsed

Any idea on this? I need to get cpu/cycles-ct values. (I am on Fedora 20. Tried updating the perf utility, it did not resolve my problem.)

Also if I run this command

perf stat -T -a sleep 1

I get the output as follows:

Performance counter stats for 'system wide':

       8022.927913      task-clock (msec)         #    8.011 CPUs utilized          
         104842699      instructions              #    0.87  insns per cycle         [100.00%]
         120099715      cycles                    #    0.015 GHz                     [100.00%]
            162615      cpu/cycles-t/             #    0.14% transactional cycles    [100.00%]
               773      cpu/tx-start/             #      210 cycles / transaction    [100.00%]
                 0      cpu/el-start/             #    0.000 K/sec                   [100.00%]
            111864      cpu/cycles-ct/            #    0.04% aborted cycles         

       1.001474976 seconds time elapsed

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