Files under the directory /sys/devices/system/cpu/cpu*/cpufreq are a set of interfaces of CPUFreq (a subsystem of the Linux kernel). By writing to some of these files, you can tell the kernel to change the behavior of the CPUs. By reading some of these files, you can get the characteristics and the current state of each core. These files are helpful when you want to know the current frequencies of the CPU cores.
scaling_cur_freq is the current frequency of the CPU in kHz.
$ cat /sys/devices/system/cpu/cpu*/cpufreq/scaling_cur_freq
800051
800017
800014
800104
800046
868286
1200551
1535523
If you have cpupower(1), it also displays the same values but in more readable MHz.
$ cpupower -c all frequency-info --freq -m
analyzing CPU 0:
current CPU frequency: 846 MHz (asserted by call to kernel)
analyzing CPU 1:
current CPU frequency: 797 MHz (asserted by call to kernel)
analyzing CPU 2:
current CPU frequency: 795 MHz (asserted by call to kernel)
analyzing CPU 3:
current CPU frequency: 800 MHz (asserted by call to kernel)
analyzing CPU 4:
current CPU frequency: 800 MHz (asserted by call to kernel)
analyzing CPU 5:
current CPU frequency: 800 MHz (asserted by call to kernel)
analyzing CPU 6:
current CPU frequency: 800 MHz (asserted by call to kernel)
analyzing CPU 7:
current CPU frequency: 1.15 GHz (asserted by call to kernel)