Subject: FFS slowness
To: None <>
From: Ivan Kanis <>
List: netbsd-users
Date: 12/22/2005 16:03:14

I am seeing poor performance with FFS + softdep. 

My machine is an AMD Opteron and it is connected to a SCSI disk
with an Adaptec 7902 Ultra320 Wide card.

The problem in a nutshell is that I am getting 1/4 of the perfomance
when copying a directory compar to copying a big file.

For example copying the /usr directory:

amd64:/# time cp -r /usr /usr.bak

real    3m44.090s
user    0m0.144s
sys     0m2.884s

amd64:/# du -sh /usr

390M    /usr

That's 1.7M/s

Copying a big ISO file:

amd64:/tmp# time cp big.iso big.iso.bak

real    1m37.254s
user    0m0.000s
sys     0m1.640s

amd64:/tmp# ls -lh big.iso
-rw-r--r--  1 root  wheel  635M Dec 22 15:18 big.iso

That's 6.6M/s

Since copying a single file is pretty fast it rules out an I/O problem
with the disk. Does anybody knows what causes the slowness? Any ideas
are welcome.

Ivan Kanis
Senior Software Developer
Tadpole Computer Limited
Tel: +44 (0) 870 432 4161

  "Deep Hack Mode--that mysterious and frighteningstate of
consciousness where Mortal Users fear to tread."
    -- Matt Welsh