Distribution:
Fedora Core 1

Hardware Environment:
Kernel: 2.6.x, vanilla, untainted, compiled with GCC 3.4.2 and GCC 2.95 vanilla
CPU: Intel Pentium 3 EB (FSB 133MHz)
MB: Asus P3V Via Apollo Pro 133 FSB 133MHz
RAM: Hyudai 256Mb PCI 133 running @ 133MHz
IDE0 channel: UDMA Mode 66Mbytes/sec (hda - Seagate 120Gb, hdb - Seagate 20Gb)
IDE1 channel: UDMA Mode 33Mbytes/sec (hdc - Sony CRX320E, hdd - Mitsumi)

Problem Description:
Steps to reproduce:
When reading files at maximum speed (no background processes/tasks running even
at runlevel 1 with only init and bash in memory) either from filesystem or
directly from /dev/hd? devices CPU load is 100% with IO wait around 60%.
The same happens when copying files within hda or hdb or from hda to hdb and
vica versa.

Tested with:
	dd if=/dev/hda of=/dev/null bs=10M
	dd if=/mnt/hda1/somefile of=/dev/null bs=10M
	cp /mnt/hda1/somefile /mnt/hda1/othername
	cp /mnt/hda1/somefile /mnt/hdb/

Windows XP Professional SP2 consumes around 92% CPU when copying files between
two HDDs on the same IDE cable and around 50% when reading/writing files.

Expected results:
CPU load as in Windows XP or less (otherwise what for is DMA intended for).

This situation happpens even if I leave the only hda device (with all others
unplugged). /dev/proc entries and lspci -vvv output are attached