cvs commit: src/sys/dev/ata ata-all.c ata-all.h ata-chipset.cata-dma.c ata-pci.c ata-pci.h

Alexander Leidinger Alexander at Leidinger.net
Tue Apr 8 07:16:21 PDT 2003


On Tue, 08 Apr 2003 15:54:43 +0200
Dag-Erling Smorgrav <des at ofug.org> wrote:

> Alexander Leidinger <Alexander at Leidinger.net> writes:
> > Does this mean we can't use ATA-TQ in situations where we would use TQ
> > without WC on a SCSI system (read: does it affect softupdates)?
> 
> Tagged queueing doesn't make sense without a write cache.  Think about
> it for a minute.

It doesn't make sense without some kind of a buffer, I know. With SCSI
disks you can observe a small difference between TQ with WC enabled and
TQ with WC disabled. Based upon this I concluded, that SCSI disks seems
to have a buffer for the WC (with all it's ill side effects in the
softupdates case) and another buffer for TQ.

SCSI != ATA, but why design another WC/TQ combination, if I can borrow
it from the SCSI disks...

Feel free to correct misunderstandings on my side.

Bye,
Alexander.

-- 
   "One world, one web, one program"  -- Microsoft promotional ad
         "Ein Volk, ein Reich, ein Fuehrer"  -- Adolf Hitler

http://www.Leidinger.net                       Alexander @ Leidinger.net
  GPG fingerprint = C518 BC70 E67F 143F BE91  3365 79E2 9C60 B006 3FE7


More information about the cvs-src mailing list