ondemand governor and encryption, low performance

[gößbrühe]

hi all,

i just installed a new system and restored my data with the most recent backup.
backup media was a 2tb external usb2 harddrive encrypted with aes and twofish, restore target was my encrypted home folder on an encrypted lvm logical volume. restore was done via rsync (-WHav --progress), which is also used to make the backups.
i started the restore at evening to leave it running unattended over night because i knew it would take some time (1.4t of data). next morning i checked and saw that the restore speed topped out at 15mb/s … way too slow.
after a little bit of checking (iowait, cpu load) i realized that the ondemand governor would not speed up the cores though due to decryption/encryption this would be desired. switching to the performance governor brought the restore speed to the expected 25mb/s (usb2).

so… is it possible to tell "the kernel" to speed up the cores in ondemand mode when encryption/decryption occures?

[gößbrühe]

i think i got it.

the ondemand governor by default scales the cpu frequency up when there is 95% load (on one core?).
below script in /etc/rc.local first makes sure the ondemand governer is running, and then sets the treshold to 30% load.

if that doesnt fix the problem i'll post it here, else case closed

for a in /sys/bus/cpu/devices/cpu?/cpufreq/scaling_governor
do
    echo 'ondemand' > ${a}
done

echo 30 > /sys/devices/system/cpu/cpufreq/ondemand/up_threshold

[dmeyer]

hi all,

i just installed a new system and restored my data with the most recent backup.
backup media was a 2tb external usb2 harddrive encrypted with aes and twofish, restore target was my encrypted home folder on an encrypted lvm logical volume. restore was done via rsync (-WHav --progress), which is also used to make the backups.
i started the restore at evening to leave it running unattended over night because i knew it would take some time (1.4t of data). next morning i checked and saw that the restore speed topped out at 15mb/s … way too slow.
after a little bit of checking (iowait, cpu load) i realized that the ondemand governor would not speed up the cores though due to decryption/encryption this would be desired. switching to the performance governor brought the restore speed to the expected 25mb/s (usb2).

so… is it possible to tell "the kernel" to speed up the cores in ondemand mode when encryption/decryption occures?

What CPU do you have? What type of encryption etc. etc. Tell us about your system.