Date: Mon, 26 Mar 2007 22:55:39 -0300 From: "Marc G. Fournier" <freebsd@hub.org> To: freebsd-questions@freebsd.org Subject: mdconfig device no faster then direct disk ... Message-ID: <A9FC3123E859D7647C969090@ganymede.hub.org>
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On a machine that is doing 0 swapping:
last pid: 47437; load averages: 0.01, 0.01, 0.00
45 processes: 1 running, 44 sleeping
CPU states: 0.0% user, 0.0% nice, 0.4% system, 0.4% interrupt, 99.2% idle
Mem: 35M Active, 285M Inact, 271M Wired, 44K Cache, 111M Buf, 402M Free
Swap: 2007M Total, 2007M Free
I just did:
mdconfig -a -t malloc -s 200m -o reserve
newfs /dev/md0
Now, my understanding, this builds a file system 'in core', vs on the disk ...
with memory being faster then disk, I would have assumed that read/write
performance would have been better, but, using iozone, I'm not finding enough
of a difference in performance to understand why I'd want to use a memory file
system:
aster# pwd
/usr
aster# iozone 180 | grep "the file"
It then reads the file. It prints the bytes-per-second
Reading the file...1.007812 seconds
54658803 bytes/second for writing the file
187280550 bytes/second for reading the file
aster# pwd
/usr
aster# cd /mnt
aster# df .
Filesystem 1K-blocks Used Avail Capacity Mounted on
/dev/md0 198126 4 182272 0% /mnt
aster# iozone 180 | grep "the file"
It then reads the file. It prints the bytes-per-second
Reading the file...0.984375 seconds
60701485 bytes/second for writing the file
191739611 bytes/second for reading the file
Am I missing something here? Or is this expected?
- ----
Marc G. Fournier Hub.Org Networking Services (http://www.hub.org)
Email . scrappy@hub.org MSN . scrappy@hub.org
Yahoo . yscrappy Skype: hub.org ICQ . 7615664
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