SCSI driver speeds

[Svante Signell <svante.signell@telia.com>]

Hello,

After trying the new and old aic7xxx drivers for kernel 2.2.13 one can
conclude that Adaptec's drivers are not always the best (maybe some
tweaking is missing, this is with the default settings):

New aic7xxx:

Boot message:
(scsi0:A:6): 11.626MB/s transfers (5.813MHz, offset 8, 16bit)
kernel: scsi0:0:6:0: Tagged Queuing enabled.  Depth 253
Later after boot:
kernel: (scsi0:A:6:0): Locking max tag count at 64

hdparm -t /dev/sda
/dev/sda:
 Timing buffered disk reads:  64 MB in  6.84 seconds =  9.36 MB/sec

Old aic7xxxx:
Boot message:
kerrnel: (scsi0:0:6:0) Synchronous at 40.0 Mbyte/sec, offset 8.
hdparm -t /dev/sda
/dev/sda:
 Timing buffered disk reads:  64 MB in  3.34 seconds = 19.16 MB/sec

As a reference the IDE speed is:
hdparm -t /dev/hda
 /dev/hda:
 Timing buffered disk reads:  64 MB in  3.55 seconds = 18.03 MB/sec

I'm running Debian/unstable, kernels are compiled by hand, using make-kpkg.
sda is an IBM 8.5+GB DNES-309170W with a main board controller aic7895C Ultra-wide

Vendor: IBM       Model: DNES-309170W      Rev: SA30
Type:   Direct-Access                      ANSI SCSI revision: 03

scsi0 : Adaptec AIC7XXX EISA/VLB/PCI SCSI HBA DRIVER, Rev 6.2.1
        <Adaptec aic7895 Ultra SCSI adapter>
        aic7895C: Ultra Wide Channel A, SCSI Id=7, 32/255 SCBs

Please forward this to the kernel-list if necessary, in order _not_ to
remove support for the old SCSI aic7xxx driver.