Untested, probably doesn't work.

bench.py

#!/usr/bin/env python
#
#                         DANGEROUS!
#
#  Benchmark drive with bonnie using ext4: vanilla, LUKS, LVM, LUKS + LVM
import os
import time
import sys

from sh import (
    chown,
    cryptsetup,
    dmsetup,
    lvcreate,
    lvremove,
    mkdir,
    mkfs,
    mount,
    pvcreate,
    pvremove,
    umount,
    vgcreate,
    Command,
)

DISK = "/dev/sde"
RUNS = 1
RESULTS_DIR = "samsung-evo840"

########################################################
#  No need to edit anything below for normal usage.    #
########################################################


PART = f"{DISK}1"
CRYPT_VOLUME_NAME = "crypt-benchmark"
CRYPT_VOLUME = f"/dev/mapper/{CRYPT_VOLUME_NAME}"
USER = "lulu"
MOUNTPOINT = "/mnt"
BONNIEDIR = f"{MOUNTPOINT}/bonnie"
PASSWORD = "MUCHSECURE"
VOLUME_NAME = "benchmark"
VOLUME_GROUP = "vg"
VG_PATH = f"/dev/{VOLUME_GROUP}/{VOLUME_NAME}"
START = 1
RUNS = 3

bonnie = Command("bonnie++")


def run_bonnie(name):
    rundir = os.path.join(RESULTS_DIR, name)
    mkdir("-p", rundir)
    for it in range(START, START + RUNS):
        result = bonnie("-d", BONNIEDIR, "-n", "1", "-u", USER)
        fname = os.path.join(rundir, "f{it}.txt")
        with open(fname) as f:
            print(result, file=f)
    chown("-R", USER, rundir)


def test_unencrypted():
    print("Testing ext4 unencrypted.")
    format_disk(PART)
    mount_volume(PART)
    run_bonnie("ext4")


def test_luks():
    print("Testing LUKS.")
    setup_luks()
    format_disk(CRYPT_VOLUME)
    mount_volume(CRYPT_VOLUME)
    run_bonnie("luks")


def test_lvm():
    print("Testing LVM.")
    setup_lvm(PART)
    format_disk(VG_PATH)
    mount_volume(VG_PATH)
    run_bonnie("lvm")


def test_luks_lvm():
    print("Testing LUKS LVM.")
    setup_luks()
    setup_lvm(CRYPT_VOLUME)
    format_disk(VG_PATH)
    mount_volume(VG_PATH)
    run_bonnie("luks_lvm")


def setup_luks():
    print("Setting up LUKS.")
    cryptsetup("luksFormat", PART, _in=PASSWORD)
    # echo $PASSWORD |  cryptsetup luksFormat PART
    print("Opening crypt volume.")
    # echo $PASSWORD | cryptsetup luksOpen PART" "$CRYPT_VOLUME_NAME
    cryptsetup("luksOpen", PART, CRYPT_VOLUME_NAME, _in=PASSWORD)


def setup_lvm(volume_path):
    print("Setting up LVM.")
    pvcreate("-y", volume_path)
    vgcreate(VOLUME_GROUP, volume_path)
    lvcreate("-l", "100%FREE", "-n", VOLUME_NAME, VOLUME_GROUP)


def format_disk(path):
    mkfs.ext4(path)


def mount_volume(volume_path):
    mount(volume_path, MOUNTPOINT)
    mkdir("-p", BONNIEDIR)
    chown(USER, BONNIEDIR)


def clean():
    print("Unmounting file systems.")
    umount(MOUNTPOINT)
    print("Removing logical volumes.")
    lvremove("-y", VOLUME_GROUP, VOLUME_NAME)
    print("Removing logical volume group.")
    lvremove("-y", VOLUME_GROUP)
    print("Removing physical volume group.")
    pvremove("-y", "-ff", CRYPT_VOLUME)
    pvremove("-y", "-ff", PART)
    time.sleep(1)
    print("Removing device.")
    dmsetup("remove", CRYPT_VOLUME)


def run():

    if os.getuid() != 0:
        print("Needs root. :(", file=sys.stderr)
        sys.exit(1)

    clean()
    test_unencrypted()

    clean()
    test_luks()

    clean()
    test_lvm()

    clean()
    test_luks_lvm()


if __name__ == "__main__":
    run()