High CPU usage for disk I/O while DMA is enabled

Hi,

my CPU usage goes up to 100% while copying files from CD to HDD or from HDD to HDD.
I have enabled DMA successfully on all of my HDD.

<snip>
/dev/hda:

 multcount    =  0 (off)
 IO_support   =  0 (default 16-bit)
 unmaskirq    =  0 (off)
 using_dma    =  1 (on)
 keepsettings =  0 (off)
 readonly     =  0 (off)

readahead = 256 (on)
geometry = 19929/255/63, sectors = 320173056, start = 0
</snip>

I am experiencing this since my Kernel upgrade from the 2.4.x series to the current 2.6.7 Kernel.
So DMA is definetely running on my box. But the CPU is utilizing too much while copying files.

Is there anything that I have forgot to consider in the "new" 2.6.x Kernel series for DMA settings?

Thanks for any hints!

--
Nesimi Buelbuel <[email protected]>
PGP-Key-ID: 0x2FAE691C
"This World is about to be Destroyed!"

Maybe you don't have the right IDE driver configured (CONFIG_BLK_DEV_*)...

Rudo.

actually I have compiled it into the Kernel.

here is a grep from all DMA related Kernel options:

CONFIG_GENERIC_ISA_DMA=y
CONFIG_BLK_DEV_IDEDMA_PCI=y
# CONFIG_BLK_DEV_IDEDMA_FORCED is not set
CONFIG_IDEDMA_PCI_AUTO=y
CONFIG_IDEDMA_ONLYDISK=y
CONFIG_BLK_DEV_ADMA=y
CONFIG_BLK_DEV_IDEDMA=y
# CONFIG_IDEDMA_IVB is not set
CONFIG_IDEDMA_AUTO=y

Nesimi

What is your motherboard ???
You must enable in .config the right IDE busmaster for your mobo.

Rafael.