LUKS Benchmark

1 Context

Hardware

Lenovo ThinkPad X230 (laptop)
Intel core i5-3320M @ 2.60 GHz (dual core, 2 threads/core)
8-GB RAM
128-GB Samsung MZ7TD128 SDD

Linux distribution

CentOS 8.1

Filesystem configuration (in logical volumes)

LUKS-encrypted 20-GiB ext4 mounted on /data1
Unencrypted 20-GiB ext4 mounted on /data2

2 Benchmark Exercise

4.4-GB data file duplication time

Using testfile.dat, a 4.4-GB data file, perform the following commands 5 times

rm testfile-copy.dat ; time cp testfile.dat testfile-copy.dat

and compute the average time for both

plain ext4 (/data2), and
encrypted ext4 (/data1) filesystems.

3 Benchmark Result

Measurement (5 runs average)

Time (s)	Plain ext4	Encrypted	Penalty
Elapsed	31.242	42.186	+35%
User	0.031	0.034	+10%
System	3.760	4.175	+11%

Statistics reported

Elapsed (or Real) time is the clock time - time from start to finish of the call. This is all elapsed time including time slices used by other processes and time the process spends blocked (for example if it is waiting for I/O to complete).
User time is the amount of CPU time spent in user-mode code (outside the kernel) within the process. This is only actual CPU time used in executing the process. Other processes and time the process spends blocked do not count towards this figure.
System time is the amount of CPU time spent in the kernel within the process. This means executing CPU time spent in system calls within the kernel, as opposed to library code, which is still running in user-space. Like 'user', this is only CPU time used by the process.

4 Raw Statistics

The following lists the raw output of the "time copy 4GBdatafile" commands, used to compute above table of figures averaged across the 5 runs

4.1 Plain ext4

Run#1
	real    0m32.086s
	user    0m0.038s
	sys     0m3.864s

Run#2
	real    0m32.046s
	user    0m0.031s
	sys     0m3.839s

Run#3
	real    0m31.948s
	user    0m0.040s
	sys     0m3.813s

Run#4
	real    0m30.725s
	user    0m0.028s
	sys     0m3.683s

Run#5
	real    0m29.407s
	user    0m0.020s
	sys     0m3.602s

4.2 LUKS-encrypted ext4

Run#1
	real    0m45.582s
	user    0m0.032s
	sys     0m4.254s

Run#2
	real    0m40.677s
	user    0m0.040s
	sys     0m4.196s

Run#3
	real    0m43.757s
	user    0m0.031s
	sys     0m4.188s

Run#4
	real    0m40.796s
	user    0m0.039s
	sys     0m4.136s

Run#5
	real    0m40.120s
	user    0m0.029s
	sys     0m4.103s