I make few tests with different frequencies of CPU / L2 cache / mem,
for small quantities of data difference is 0 or small , but in other tests I received
dramatic difference.
(LinkSys EA8500, IPQ8064 1.4Ghz)
For example, compression with XZ (lzma2 method, 8Mb dict., 6 level of compression , 95Mb memory used) :
performance governor ,
use RAmDisk in /tmp
tar -cf - /usr/ > /tmp/test.tar
ls -la /tmp/test.tar
-rw-r--r-- 1 root root 18684928 Jan 13 23:31 /tmp/test.tar
top
PID PPID USER STAT VSZ %VSZ %CPU COMMAND
12928 12927 root R 96220 20% 50% xz -6 -c test.tar
ps | grep xz
12927 root 1064 S time xz -6 -c test.tar
12928 root 96220 R xz -6 -c test.tar
test :
time xz -6 -c test.tar > test.tar.xz
echo 384000 > /sys/devices/system/cpu/cpufreq/policy0/scaling_max_freq
echo 384000 > /sys/devices/system/cpu/cpufreq/policy1/scaling_max_freq
cat /sys/devices/system/cpu/cpu*/cpufreq/cpuinfo_cur_freq
384000
384000
real 2m 20.71s
real 2m 21.17s
it's CPU 384 Mhz , frequencies of / L2 cache / mem always the same (low)
echo 600000 > /sys/devices/system/cpu/cpufreq/policy0/scaling_max_freq
echo 600000 > /sys/devices/system/cpu/cpufreq/policy1/scaling_max_freq
cat /sys/devices/system/cpu/cpu*/cpufreq/cpuinfo_cur_freq
600000
600000
real 1m 44.50s (user 1m 43.84s sys 0m 0.58s)
real 1m 44.47s
it's CPU 600 Mhz , frequencies of / L2 cache / mem always the same
echo 800000 > /sys/devices/system/cpu/cpufreq/policy0/scaling_max_freq
echo 800000 > /sys/devices/system/cpu/cpufreq/policy1/scaling_max_freq
cat /sys/devices/system/cpu/cpu*/cpufreq/cpuinfo_cur_freq
800000
800000
real 1m 27.01s
real 1m 26.96s
it's CPU 800 Mhz , frequencies of / L2 cache / mem always the same
echo 1000000 > /sys/devices/system/cpu/cpufreq/policy0/scaling_max_freq
echo 1000000 > /sys/devices/system/cpu/cpufreq/policy1/scaling_max_freq
cat /sys/devices/system/cpu/cpu*/cpufreq/cpuinfo_cur_freq
1000000
1000000
real 0m 59.55s
real 0m 59.53s
it's CPU 1000 Mhz with high (for 1000 mhz) frequencies of / L2 cache / mem
echo 1200000 > /sys/devices/system/cpu/cpufreq/policy0/scaling_max_freq
echo 1200000 > /sys/devices/system/cpu/cpufreq/policy1/scaling_max_freq
cat /sys/devices/system/cpu/cpu*/cpufreq/cpuinfo_cur_freq
1200000
1200000
real 1m 8.98s
real 1m 9.02s
it's CPU 1200 Mhz with low (for 1200 mhz) frequencies of / L2 cache / mem
echo 1400000 > /sys/devices/system/cpu/cpufreq/policy0/scaling_max_freq
echo 1400000 > /sys/devices/system/cpu/cpufreq/policy1/scaling_max_freq
cat /sys/devices/system/cpu/cpu*/cpufreq/cpuinfo_cur_freq
1400000
1400000
real 1m 3.71s
real 1m 3.59s
it's 1400 Mhz with low (for 1400 mhz) frequencies of / L2 cache / mem
echo 800000 > /sys/devices/system/cpu/cpufreq/policy0/scaling_max_freq
echo 800000 > /sys/devices/system/cpu/cpufreq/policy1/scaling_max_freq
echo 1400000 > /sys/devices/system/cpu/cpufreq/policy0/scaling_max_freq
echo 1400000 > /sys/devices/system/cpu/cpufreq/policy1/scaling_max_freq
cat /sys/devices/system/cpu/cpu*/cpufreq/cpuinfo_cur_freq
1400000
1400000
real 0m 45.12s
real 0m 45.19s
it's CPU 1400 Mhz with high (for 1400 mhz) frequencies of / L2 cache / mem
echo 800000 > /sys/devices/system/cpu/cpufreq/policy0/scaling_max_freq
echo 800000 > /sys/devices/system/cpu/cpufreq/policy1/scaling_max_freq
echo 1000000 > /sys/devices/system/cpu/cpufreq/policy0/scaling_max_freq
echo 1000000 > /sys/devices/system/cpu/cpufreq/policy1/scaling_max_freq
cat /sys/devices/system/cpu/cpu*/cpufreq/cpuinfo_cur_freq
1000000
1000000
real 0m 59.56s
it's CPU 1000 Mhz with high (for 1000 mhz) frequencies of / L2 cache / mem
echo 1200000 > /sys/devices/system/cpu/cpufreq/policy0/scaling_max_freq
echo 1200000 > /sys/devices/system/cpu/cpufreq/policy1/scaling_max_freq
echo 1000000 > /sys/devices/system/cpu/cpufreq/policy0/scaling_max_freq
echo 1000000 > /sys/devices/system/cpu/cpufreq/policy1/scaling_max_freq
cat /sys/devices/system/cpu/cpu*/cpufreq/cpuinfo_cur_freq
1000000
1000000
real 1m 16.21s
it's CPU 1000 Mhz with low frequencies of / L2 cache / mem