[Alug] Hard Drive performance Part 2
fozzy at pelvoux.demon.co.uk
Fri Sep 20 00:15:02 BST 2002
On Thu, 19 Sep 2002 23:42:05 +0100
Steve Fosdick <fozzy at pelvoux.demon.co.uk> wrote:
> The most likely of these if probably that the drive capability info says the drive doesn't support DMA so the next thing would be to find out where the IDE driver gets that from, whether it is from the drive itself or from the BIOS.
Further to my last message, I have found what appear to be the rules for whether Linux uses DMA automatically (i.e. without hdparm setting it on).
1. If the drive model number is on the bad list then don't use DMA and don't check any further. Drives on this list as of Kernel 2.4.19 are:
SANYO CD-ROM CRD
Toshiba CD-ROM XM-6202B
E-IDE CD-ROM CR-840
RICOH CD-R/RW MP7083A
SAMSUNG CD-ROM SC-148C
SAMSUNG CD-ROM SC-148F
SAMSUNG CD-ROM SC
SAMSUNG CD-ROM SN-124
PLEXTOR CD-R PX-W8432T
ATAPI CD-ROM DRIVE 40X MAXIMUM
2. If the BIOS has enabled DMA on the drive then leave it on and set Linux to use it.
3. If the drive is a known good list then turn DMA on. Drives on the good list are:
CONNER CTMA 4000
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