On 02/12/18 on 13:08, info at smallinnovations dot nl wrote:
>
> If you disable journalling on ext4 you can just as well mount it with
> ext2 afaik.
>
> Grtz
>
> Nick
>

  No, ext2 is significantly slower than a journal-less ext4 filesystem.

  This must be due mainly to the fact that ext4 uses an improved
block-allocator algorithm, one that merges the allocation of a series of
blocks to the same file in one run instead of $FILE_SIZE/$BLOCK_SIZE
runs.  I recently run a comparison test on an old 1GB USB pendrive
connected to a USB-2 port, here you are with the log:


[alessandro@wkstn02 ~]$ cat bin/bomb_filesystem.sh
#!/bin/dash

TESTROOT=/mnt/loop
MAXDIRS=100
MAXFILES=10

if mountpoint --quiet "$TESTROOT"
then I=0
     while test "$I" -lt "$MAXDIRS"
     do mkdir "$TESTROOT/Dir_$I" || break
        I=$((I+1))
     done
     I=0
     while test $I -lt "$MAXDIRS"
     do J=0
        while test $J -lt "$MAXFILES"
        do dd count=$((1024+16*J)) if=/dev/zero
of="$TESTROOT/Dir_$I/file_$J"
           J=$((J+1))
        done
        I=$((I+1))
     done
else echo "ERROR: \"$TESTROOT\" does not exist or is not a mountpoint" >&2
     exit 1
fi


[root@wkstn02 ~]# mkfs.ext2 /dev/sdb
[root@wkstn02 ~]# mount /dev/sdb /mnt/loop
[root@wkstn02 ~]# chown alessandro /mnt/loop


[alessandro@wkstn02 ~]$ time (bomb_filesystem.sh ; sync)

real    10m35,149s
user    0m1,042s
sys     0m1,921s

[alessandro@wkstn02 ~]$ df /mnt/loop
File system     Size Used Avail Use% Mounted on
/dev/sdb        953M  541M    364M  60% /mnt/loop


[alessandro@wkstn02 ~]$ time (\rm -r /mnt/loop/Dir_* ; sync)

real    0m2,133s
user    0m0,009s
sys     0m0,076s

[alessandro@wkstn02 ~]$ time (bomb_filesystem.sh ; sync)

real    11m10,261s
user    0m0,961s
sys     0m2,109s


[root@wkstn02 ~]# umount /dev/sdb
[root@wkstn02 ~]# mkfs.ext4 -O ^has_journal /dev/sdb
[root@wkstn02 ~]# mount /dev/sdb /mnt/loop
[root@wkstn02 ~]# chown alessandro /mnt/loop


[alessandro@wkstn02 ~]$ time (bomb_filesystem.sh ; sync)

real    3m39,434s
user    0m1,024s
sys     0m1,950s

[alessandro@wkstn02 ~]$ time (\rm -r /mnt/loop/Dir_* ; sync)

real    0m2,486s
user    0m0,002s
sys     0m0,082s


 

--
Alessandro Selli <alessandroselli@???>
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