while booting my new kernel 2.6.8.1, i get an error like this :

"DMA on your HDD turned off. Ýt may slow down fsck process"

How can i fix it, did i misconfigure my kernel????!!!!
Which module should i remove or install to fix it???
PS: Ý use reiserfs file system

My machine slowed down.it waits 10 second to open mozilla browser every time....same for gnome-terminal

does it have somethind to do with that DMA thinG??

man hdparm or search the forums. There is a rather large thread regarding setting these parameters.

As root:

# hdparm /dev/hda
# hdparm -Tt /dev/hda
# hdparm --help

HTH

thnx..i'll give it a try

To turn on dma do hdparm -d1 /dev/hdx

To check if it is turned on after this do hdparm -i /dev/hdx and it will tell you, or just do another benchmark, it should be much faster. Note that if you have to turn on dma manually it will reset every reboot so you need to add that command to /etc/rc.d/rc.local.

But it sounds like you don't have dma turned on in your kernel. May have to recompile and make sure you look for the dma option in the config process.

I had googled to make sure there wasn't a difference between 2.4 and 2.6 kernels and hdparm and I found some interesting references to 2.6.8-1 kernel and poor hard drive performance - as in bad hdparm numbers that were not there with 2.6.7. You may want to google this and keep up to date with this issue.

Just an FYI

I ahd the same thing happen the other day. Has to do wit hyour kernel configuration options. You need to make sure you have selected to automatically enable DMA. Don't remember the xact options, but I eventually got it working. I think it is a better solution thatn hdparm, but it's gonna take more time to figure out which options you need to choose.

Good luck,

I'm using 2.6.8.1 and have very good performance:

Thats just an average hard drive that came with my pos dell dimension 2400

Do I have anything missing in the kernel config?
cat .config | grep "DMA"

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 is not set
CONFIG_BLK_DEV_ADMA=y
CONFIG_BLK_DEV_IDEDMA=y
# CONFIG_IDEDMA_IVB is not set
CONFIG_IDEDMA_AUTO=y

P.S. I was told that hdparm can lose the data on your harddrive and use with care, is it true?

hello to all!
acording to the posts,many of you has solved the DMA issue in the kernel-2.6.xx,if so could aomeone explain it please?

howto set DMA

hi!does someone know how to set DMA on in kernel-2.6.xx?I know the kernel-2.4.26 sets on by default,but 2.6.xx doesn't.when I command like this -------->/dev/hda:
setting using_dma to 1 (on)
HDIO_SET_DMA failed: Operation not permitted
using_dma = 0 (off)

with 2.4.26 no need to command.I tried to look for and to enable from the kernel-2.6.xx menu,but I couldn't find place where from to enable.does someone know exact place in the kernel-2.6.xx menu or where to enable DMA from?thanks!

DMA is set automatically at boot time for me. I'm using the 2.6.8.1 kernel. Here's the relevant parts of my config.

this my config,but DMA is not set on auto eventough I have command in rc.local

moonloader@moonloader:/usr/src/linux-2.6.8.1# cat .config | grep "DMA"
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 is not set
CONFIG_BLK_DEV_ADMA=y
CONFIG_BLK_DEV_IDEDMA=y
# CONFIG_IDEDMA_IVB is not set
CONFIG_IDEDMA_AUTO=y
CONFIG_IEEE1394_SBP2_PHYS_DMA=y

hello to all!
I found out how to set the DMA on and it same for the kernel-2.4.xx and kernel-2.6.xx.this is how I did it and I hope this post will help to the people who has same issue or who wants to set DMA on.

ATA/ATAPI/API/MFM/RLL support yes
PCI IDE chipset support yes
Generic PCI bus-master DMA support yes
then I chose All options in same menu (what effect to set DMA on!!!)

results success!

/dev/hda:
using_dma = 1 (on)