Re: 2.4.21 ServerWorks DMA Bugs

[Markus Plail <linux-kernel@gitteundmarkus.de>]

On Fri, 4 Jul 2003, Ryan Mack wrote:

> I've real the other threads but nothing touches on my specific issue.
> I have a dual P4 Xeon Dell PowerEdge 1600SC with a Fusion MPT SCSI
> controller and a ServerWorks CSB5 IDE chipset.  All the HDs are on the
> SCSI bus, and only my CD reader and my DVD writer are on the IDE bus
> (one on each channel).  Hyperthreading is enabled (4 logical
> processors).  I am using GCC 3.2.2.
> 
> The CD readers is the blacklisted 'SAMSUNG CD-ROM SC-148C' and I never
> use it so I can remove it if needed.  The DVD writer is a 'SONY DVD RW
> DRU-500A'.  Both are going through the ide-scsi driver.  Whenever I
> read/write CDs in the DVD writer, I get very high system load (50% on
> one CPU), even though DMA seems to be enabled.

If you are writing CDs with unusual block sizes (audio CDs, (S)VCDs,
RAW mode -> blocksize != 2048) you won't get DMA with ide-scsi, no
matter what you do. It's simply not supported.

regards
Markus