cpu-freq: running the perf increases the data rate?

[Subhashini Rao Beerisetty]

 [ Please keep me in CC as I'm not subscribed to the list]

Hi all,

I have an application which finds the data rate over the PCIe
interface. I’m getting the lesser data rate in one of my Linux X86
systems.
When I change the scaling_governor from "powersave" to "performance"
mode for each CPU, then there is slight improvement in the PCIe data
rate.
Parallely I started profiling the workload with perf. Whenever I start
running the profile command “perf stat -a -d -p <PID>” surprisingly
the application resulted in excellent data rate over PCIe, but when I
kill the perf command again PCIe data rate drops. I am really confused
about this behavior.Any clues from this behaviour?


Also I noticed my system not having the 'cpuinfo_cur_freq' sys file.
Is that okay?
cat: /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_cur_freq: No such
file or directory


-- 
Thanks,