gistfile1.txt

#!/bin/bash

set -e

set_sched()
{
	TARGET_DEV=$1
	TARGET_SCHED=$2
	echo $TARGET_SCHED > /sys/block/$TARGET_DEV/queue/scheduler
}
if [[ $# -ne 7 ]]; then
	echo "Usage: <$0> <fs-blocksize> <file-size> <data-blocksize> <io-sched>"
	echo "Examples:"
	echo "$0 4k 1GiB 4MiB /dev/nvme0n1 /dev/nvme1n1 /mnt-nvme kyber"
	echo "$0 4k 1GiB 4MiB /dev/nvme0n1 /dev/nvme1n1 /mnt-nvme mq-deadline"
	echo "$0 4k 1GiB 4MiB /dev/nvme0n1 /dev/nvme1n1 /mnt-nvme none"
	echo "$0 4k 1GiB 4MiB /dev/nvme0n1 /dev/nvme1n1 /mnt-nvme bfq"
	exit
fi

BS=$1
FILE_SIZE=$2
DATA_BS=$3
DATA_DEV=$4
DDEV=$(basename $DATA_DEV)
LOGDEV=$5
LDEV=$(basename $LOGDEV)
MNT_PATH=$6
SCHED=$7

mkdir -p $MNT_PATH

if grep -q $MNT_PATH /proc/mounts; then
	umount $MNT_PATH
fi

nvme format --lbaf=1 --force $DATA_DEV
nvme format --lbaf=1 --force $LOGDEV

#mkfs.xfs -f -b size=$BS -d agcount=32,sectsize=4k $DATA_DEV -i size=2048 -m reflink=0 -l logdev=$LOGDEV,size=2020m,sectsize=4k
#mkfs.xfs -f -b size=$BS -d agcount=32,sectsize=4k $DATA_DEV -m reflink=0 -i nrext64=1 -l logdev=$LOGDEV,size=2020m,sectsize=4k

mkfs.xfs -f -b size=$BS -d agcount=32,sectsize=4k $DATA_DEV -m reflink=0 -l logdev=$LOGDEV,size=2020m,sectsize=4k

mount $DATA_DEV -o logdev=$LOGDEV,noatime $MNT_PATH

case $SCHED in
	# https://docs.kernel.org/block/kyber-iosched.html
	kyber)
		set_sched $DDEV kyber
		set_sched $LDEV kyber

		# default is 2000000 in nanoseconds
		#echo 2000000 > /sys/block/$DDEV/queue/iosched/read_lat_nsec
		
		# default is 10000000 in nanoseconds
		#echo 10000000 > /sys/block/$DDEV/queue/iosched/write_lat_nsec
		;;
	# https://docs.kernel.org/block/bfq-iosched.html
	bfq)
		set_sched $DDEV bfq
		set_sched $LDEV bfq

		# Disable low latency, its enabled by default
		echo "Disabling low latency for bqf"
		echo 0 > /sys/block/$DDEV/queue/iosched/low_latency
		echo 1 > /sys/block/$LDEV/queue/iosched/low_latency

		# default is 124, milliseconds
		#echo 10000 > /sys/block/$DDEV/queue/iosched/timeout_sync
		
		# default is 0, so disabled. Max sectors to service
		#echo 16384 > /sys/block/$DDEV/queue/iosched/max_budget
		#
		# 4 MiB
		#echo 4194304 > /sys/block/$DDEV/queue/iosched/max_budget
		#
		# 2 MiB
		#echo 2097152 > /sys/block/$DDEV/queue/iosched/max_budget
		#
		# 64k
		#echo 65536 > /sys/block/$DDEV/queue/iosched/max_budget
		;;
	# https://docs.kernel.org/block/deadline-iosched.html
	mq-deadline)
		set_sched $DDEV mq-deadline
		set_sched $LDEV mq-deadline

		#async_depth fifo_batch front_merges prio_aging_expire read_expire write_expire writes_starved
		
		echo 0 > /sys/block/$DDEV/queue/iosched/front_merges
		# Default is 16.
		
		# 2 MiB?
		echo 512 > /sys/block/$DDEV/queue/iosched/fifo_batch

		# Default is 5000 in ms
		#echo 25000 > /sys/block/$DDEV/queue/iosched/writes_starved
		;;
	*)
		# Note, none is the default for NVMe and is known to be
		# the best for NVMe. There are no tunables for it as well.
		set_sched $DDEV $SCHED
		set_sched $LDEV $SCHED
		;;
esac

./go/bin/dperf -f $FILE_SIZE -b $DATA_BS -i 128 $MNT_PATH