I recently upgraded a NetBSd 2.5.1 box running a 400MHz K6-2 to a
1.4G athlon (epox 8k7a) and NetBSD 1.5.2 .  I'm running an adaptek
2940UW and some IBM DDRS-34560 4.5G drives.

(bonnie) disk performance before the upgrade:

    -------Sequential Output-------- ---Sequential Input-- --Random--
    -Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
 MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU  /sec %CPU
100 12101 64.1 11702 19.9  2968  6.1 12707 59.9 12781 13.1 112.1  1.8

after the upgrade:

    -------Sequential Output-------- ---Sequential Input-- --Random--
    -Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
 MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU  /sec %CPU
100  8698 10.5  8532  2.4  2883  1.2 10834 19.3 11974  3.4 110.0  0.9

While %cpu is way down (?), the performance is also way down.

The same machine with a Fujitsu MPF3102AH 7200rpm ATA66 :

    -------Sequential Output-------- ---Sequential Input-- --Random--
    -Per Char- --Block--- -Rewrite-- -Per Char- --Block--- --Seeks---
 MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU  /sec %CPU
100 21229 28.8 21572  7.3  4679  2.1 24954 52.1 21701  7.0 108.7  1.3

Any idea as to why the 2940 controller is running so slow now? It's
great that it isn't using much cpu time, but the machine is basically
disk-bound. Doesn't compile a whole lot faster than the 400MHz k6-2
did when using the scsi drives.

cpu0: AMD Athlon Model 4 (Thunderbird) (686-class), 1459.24 MHz
total memory = 511 MB
avail memory = 468 MB
using 6573 buffers containing 26292 KB of memory
BIOS32 rev. 0 found at 0xfb5b0
mainbus0 (root)
pci0 at mainbus0 bus 0: configuration mode 1
pci0: i/o space, memory space enabled
pchb0 at pci0 dev 0 function 0
pchb0: Advanced Micro Devices product 0x700e (rev. 0x13)
ppb0 at pci0 dev 1 function 0: Advanced Micro Devices product 0x700f (rev. 0x00)
pci1 at ppb0 bus 1
pci1: i/o space, memory space enabled
...
ahc1 at pci0 dev 9 function 0
ahc1: interrupting at irq 11
ahc1: aic7880 Wide Channel A, SCSI Id=7, 16/255 SCBs
scsibus0 at ahc1 channel 0: 16 targets, 8 luns per target
...
scsibus0: waiting 2 seconds for devices to settle...
ahc1: target 1 using 16bit transfers
ahc1: target 1 synchronous at 10.0MHz, offset = 0x8
ahc1: target 1 using tagged queuing
sd0 at scsibus0 target 1 lun 0: <IBM, DDRS-34560D, DC2D> SCSI2 0/direct fixed
sd0: 4303 MB, 8387 cyl, 5 head, 210 sec, 512 bytes/sect x 8813870 sectors
...