Hard disk access causes high CPU load

[Balazs Javor <jb3@freemail.hu>]

Hi,

How can I find out whether the hard disks in my Woody box
are using the best possible DMA mode (or any DMA at all)?

Allthough I have a relativly slow machine (VIA C3 800 + 256MB),
I have an ATA100 controller (VIA PL133) and two Seagate Barracuda IVs.
So they should be relatively fast and use not much CPU, or shouldn't
they?

But on my 2.4.18 machine it can take ages to transfer large file
between them. And while the file transfer takes place the CPU
usage is above 90% and XFree becommes _extremely_ sluggish.
Even if I try to move the mouse there are stops and a quite large lag...

Is this normal, or do I need to set up something differently?

>From dmesg I can see something like this:

Uniform Multi-Platform E-IDE driver Revision: 6.31
ide: Assuming 33MHz system bus speed for PIO modes; override with idebus=xx
VP_IDE: IDE controller on PCI bus 00 dev 39
VP_IDE: chipset revision 6
VP_IDE: not 100% native mode: will probe irqs later
    ide0: BM-DMA at 0xd000-0xd007, BIOS settings: hda:DMA, hdb:DMA
...
hda: ST380021A, ATA DISK drive
hdb: ST380021A, ATA DISK drive

(Just noticed) Under /proc/ide/hda/settings I have:

using_dma               0               0               1               rw

So it seems DMA is off, right?

What do I need to do?

Many thanks for your help in advance!
best regards,
Balazs


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