btrfs_send_test.sh

#!/bin/bash

set -e -o pipefail

SUBVOL=test
SUBVOL_RO=test_ro
DB_FILE=$SUBVOL/test.file

NUM_ENTRIES=100000000
NUM_EXTENTS=100000

uname -a

frags() {
        filefrag -v $DB_FILE | wc -l
}

mod_db() {
        echo "WITH RECURSIVE cnt_rnd(x, rnd) AS (VALUES(1, ABS(RANDOM())%$NUM_ENTRIES ) UNION ALL SELECT x+1, ABS(RANDOM())%$NUM_ENTRIES FROM cnt_rnd WHERE x<10000) UPDATE test SET rnd=RANDOM() WHERE x in (SELECT rnd FROM cnt_rnd);" | sqlite3 $DB_FILE
}


CREATE=1
if [[ $CREATE == 1 ]]; then

if test -e $SUBVOL
then
        btrfs subvol del $SUBVOL
fi

#! [ -e "$DB_FILE" ] || rm "$DB_FILE"

btrfs subvol create $SUBVOL

echo "CREATE TABLE test(x INTEGER PRIMARY KEY, rnd INTEGER); WITH RECURSIVE cnt(x, rnd) AS (VALUES(1, RANDOM()) UNION ALL SELECT x+1, RANDOM() FROM cnt WHERE x<$NUM_ENTRIES) INSERT INTO test (x, rnd) SELECT x, rnd FROM cnt;" | sqlite3 $DB_FILE

fi # CREATE=1

if test -e $SUBVOL_RO
then
        btrfs subvol del $SUBVOL_RO
fi

echo "Testing send without fragmentation..."
sync
echo 3 > /proc/sys/vm/drop_caches
btrfs subvol snap -r $SUBVOL $SUBVOL_RO
time btrfs send $SUBVOL_RO > /dev/null

FRAGS=$(frags)
while [ $FRAGS -lt $NUM_EXTENTS ]
do
        echo "Currently $DB_FILE has $FRAGS extents..."
        for i in seq 0 10
        do
                mod_db
        done
        FRAGS=$(frags)
done

echo "$DB_FILE has $FRAGS extents."

if test -e $SUBVOL_RO
then
        btrfs subvol del $SUBVOL_RO
fi

echo "Testing send with fragmentation..."
btrfs subvol snap -r $SUBVOL $SUBVOL_RO
mod_db
sync
echo 3 > /proc/sys/vm/drop_caches
time btrfs send $SUBVOL_RO > /dev/null