I've just done some benchmarks (okay, it has nothing to do with dirpref,
and file creation) but it's very interesting, as seeks the disk like a
horror:

#!/bin/sh

for a in 1 2 3 4 5 6 7 8 9 0 a b c d e f; do
	for b in 1 2 3 4 5 6 7 8 9 0 a b c d e f; do
		dd if=/dev/zero of=$a$b bs=128k count=1
	done
done

time tar cf test.tar *
time sync

Test machine: Intel PIII 800MHz / 256MB / IBM DTLA 20GB disk

And the results (first line is `tar', second line is `sync')

Test 1: NetBSD 1.5.1 FFS w/softdep
    20.38s real		0.00s user	0.50s system
     0.35s real		0.00s user	0.00s system

Test 2: NetBSD 1.5.1 FFS w/o softdep
    20.39s real		0.00s user	0.45s system
     0.40s real		0.00s user	0.00s system

Test 3: NetBSD 1.5.1 FFS w/sync
   130.38s real		0.04s user	1.11s system
     0.10s real		0.00s user	0.00s system

Test 4: FreeBSD 4.3-RC3 UFS w/softdep
     9.35s real		0.00s user	0.65s system
     0.35s real		0.00s user	0.00s system

Test 5: Linux 2.2.18 ext2fs w/async
     1.48s real		0.04s user	1.00s system
     0.10s real		0.00s user	0.02s system

Test 6: Linux 2.2.18 ext2fs w/sync
     5.63s real		0.07s user	1.50s system
     0.05s real		0.00s user	0.00s system

I can greatly improve the performance on NetBSD by passing the
'-b 8192' option to 'tar'. (In this case, performance results are
almost similar to Linux)

Is there any black magic to improve the performance on NetBSD?

-- mauzi

Gergely EGERVARY
System Administrator
Business Polytechnic, HUNGARY