I have measured write/remove time with the USB flash drive;
uhub4 at uhub0 port 5 "NEC product 0x005a" rev 2.00/1.00 addr 2
umass0 at uhub4 port 1 configuration 1 interface 0 "TOSHIBA TransMemory" rev
2.00/1.10 addr 3
umass0: using SCSI over Bulk-Only
scsibus2 at umass0: 2 targets, initiator 0
sd0 at scsibus2 targ 1 lun 0: <TOSHIBA, TransMemory, PMAP> SCSI0 0/direct
removable
sd0: 961MB, 512 bytes/sec, 1968128 sec total
First, I copied file tree (about 100MB) from mfs to such USB flash drive, then
umount.
Next, mount it again, then remove all files and directories.
(test script at the end of this mail)
Here's the data;
write files remove files
------------------- --------------------------- -------------------------
mount option real user system real user system
------------------- --------- ------- -------- --------- ------- -------
none 24m18.37s 0m1.15s 0m16.58s 14m54.99s 0m0.26s 0m5.70s
noatime 23m56.60s 0m1.03s 0m16.95s 14m32.22s 0m0.42s 0m5.59s
async 07m28.74s 0m0.79s 0m14.29s 00m06.91s 0m0.24s 0m1.90s
async,noatime 07m29.09s 0m0.87s 0m14.97s 00m07.02s 0m0.19s 0m2.06s
softdep 09m55.40s 0m0.73s 0m15.59s 04m23.48s 0m0.24s 0m2.17s
softdep,noatime 09m54.15s 0m0.90s 0m15.05s 04m27.81s 0m0.21s 0m1.99s
result: write time: none >> softdep > async
remove time: none >> softdep >> async
Both softdep and async options seem to affect write/remove times.
And especially, async option very affects remove time.
----[test script]-------------------------------------------
#!/bin/sh
for opt in none noatime async noatime,async softdep softdep,async
do
if [ X$opt = Xnone ]
then
opt=""
else
opt="-o $opt"
fi
echo ==== opt: $opt ====
if mount $opt /dev/sd0d /mnt
then
cd /mfs/ && time pax -rwpe . /mnt/tmp/.
umount /mnt
sleep 60
fi
if mount $opt /dev/sd0d /mnt
then
cd /mnt/tmp && time rm -rf *
cd
umount /mnt
sleep 60
fi
done
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