#!/bin/sh

#load the device with these params
#$ modprobe scsi_debug virtual_gb=32 delay=0 dev_size_mb=32 fake_rw=1

# go set some live params
# $ cd /sys/bus/pseudo/drivers/scsi_debug
# $ echo 1 > fake_rw

# mess with sglist chaining
# $ cd /sys/block/sdb/queue
# $ echo 4096 > max_segments
# $ cat max_hw_sectors_kb  > max_sectors_kb
# $ cat max_hw_sectors_kb 


if=/dev/zero
of=/dev/sdb

outputfile=$1.txt
echo "Testing $1"

# send 32G in $1 sectrors at once
do_dd()
{
# blocks of one sector
bs=512
#memory page in blocks
page=8
#number of scatterlist elements in a transfer
sgs=$1
#calculate the bpt param
bpt=$(($sgs*$page))
#total blocks to transfer 32 Giga bytes
count=64M


echo $3: "bpt=$bpt"

\time bash -c \
	"sg_dd blk_sgio=1 dio=1 if=$if of=$of bpt=$bpt bs=$bs count=$count 2>/dev/null" \
	2>> $2
}

echo "BEGIN RUN $1" >> $outputfile

# warm run
for i in {1..5}; do
do_dd 2048 /dev/null $i;
done

# one page trasfers
echo "one page transfers"
echo "one page transfers" >> $outputfile
for i in {1..20}; do
do_dd 128 $outputfile $i;
done

# chained
# 16K / 8 = 2K pages
# 2K / 128 = 16 chained sglists
echo "16 chained sglists"
echo "16 chained sglists" >> $outputfile
for i in {1..20}; do
do_dd 2048 $outputfile $i;
done

echo "END RUN" >> $outputfile