Enabling HDD DMA in Gentoo?

vharishankar · 03-09-2005, 12:03 AM

Hello,

I want to know how to enable DMA at startup in Gentoo Linux. And is there anything that must be compiled into the kernel to enable DMA?

I ran hdparm /dev/hda in Debian and here are the results:

Code:

/dev/hda:
 multcount    = 16 (on)
 IO_support   =  1 (32-bit)
 unmaskirq    =  1 (on)
 using_dma    =  1 (on)
 keepsettings =  0 (off)
 readonly     =  0 (off)
 readahead    =  8 (on)
 geometry     = 9733/255/63, sectors = 80060424192, start = 0

I want the DMA setting to be "on" in Gentoo as well. At the moment I get a warning about DMA not being enabled whenever Gentoo boots up. There is also a warning that it might slow down apps like KDE and so on if DMA is disabled.

XavierP · 03-09-2005, 12:49 AM

As per request, moved to Linux-Hardware

dalek · 03-09-2005, 12:50 AM

You may want to start hdparm. Usually goes like this:

Code:

/etc/init.d/hdparm start

If you get no error messages then you can add it to the boot up process like this:

Code:

rc-update add hdparm default

It should then start up during the boot up.

You may can get more info on options here.

http://www.linuxgazette.com/issue79/punk.html

Later

vharishankar · 03-09-2005, 01:12 AM

Thanks dalek. I'll try that out.

dalek · 03-09-2005, 01:22 AM

If it is not installed, emerge -v hdparm and it will install it for you. Then do the commands above. I think it is installed as part of system, not sure. Also, make sure you have the right chipset in your kernel. DMA won't work if it is not.

Later

vharishankar · 03-09-2005, 01:24 AM

Well hdparm is installed in Gentoo as well, so no problem with that.

Also as I just confirmed, DMA mode is enabled and working in Debian, so enabling DMA in Gentoo should not be a problem.

But what is the kernel option in make menuconfig for the chipsets?

vharishankar · 03-09-2005, 01:43 AM

I ran /etc/init.d/hdparm start

and I got this error

Code:

 * Starting hdparm...                                                     [ ok ]
 * Running hdparm on /dev/discs/disc0/disc...
 HDIO_SET_DMA failed: Operation not permitted
 * Running hdparm on /dev/discs/disc1/disc...
 HDIO_SET_DMA failed: Operation not permitted
 * Running hdparm on /dev/cdroms/cdrom0...
 HDIO_SET_DMA failed: Operation not permitted
 * Running hdparm on /dev/cdroms/cdrom1...
 HDIO_SET_DMA failed: Operation not permitted

I'm typing this from Gentoo and KDE is really slow

dalek · 03-09-2005, 02:16 AM

You may have the wrong chipset in the kernel. You may have to search around to find out what chip is used and put it in the kernel. It is sort of the same principle as installing a driver for your video card except it is a kernel thing.

I don't run hdparm on mine, it is installed though. I actually started mine when responding to your question. It runs slower with it than without it. You may want to make sure you have the right chipset enabled in the kernel and test the thing before using hdparm. Test this way:

Code:

hdparm -Tt /dev/hd<your drive letter here, a for first drive; b for second etc etc >

Hope that helps. Time for shut eye over here. It's after 2:00AM here.

Later

vharishankar · 03-09-2005, 02:19 AM

Just to confirm, I compiled all the IDE/DMA chipset modules available as modules, but I am not sure which chipset is the right one for me.

vharishankar · 03-09-2005, 02:46 AM

Done it! It works and even without hdparm at all.

I just compiled the Nvidia/AMD IDE chipset drivers into the kernel rather than as a module and rebooted and the performance is much much better now.

The option to find is "Device Drivers" --> "ATA/ATAPI/MFM/RLL support" in

Code:

make menuconfig

(kernel 2.6).

Didn't need to bother with hdparm at all!

Thanks for your help dalek.

For those interested. Test results of hdparm -Tt /dev/hdb

With the IDE chipset drivers compiled *with* hdparm started the result is:

Code:

/dev/hdb:
 Timing cached reads:   1144 MB in  2.00 seconds = 570.94 MB/sec
 Timing buffered disk reads:  164 MB in  3.02 seconds =  54.28 MB/sec

With the IDE chipset drivers compiled *without* hdparm started the result is:

Code:

/dev/hdb:
 Timing cached reads:   1224 MB in  2.00 seconds = 610.87 MB/sec
 Timing buffered disk reads:  162 MB in  3.01 seconds =  53.74 MB/sec

Not much difference there.

dalek · 03-09-2005, 04:36 AM

Sounds about right. The drive is the big issue here. It seems that the manufacturer can have a lot to do with the speed. I have two 80GB drives and the fast one is in this rig. The other is just over half as fast as this one. This is mine with KDE and all that stuff running of course.

Code:

root@smoker / # hdparm -Tt /dev/hda

/dev/hda:
 Timing cached reads:   1744 MB in  2.00 seconds = 871.70 MB/sec
 Timing buffered disk reads:  170 MB in  3.00 seconds =  56.64 MB/sec
root@smoker / #

I noticed it dropped just a little but when I started hdparm though. Prolly need to set it up with different options.

Glad you got that far though. I like learning something new every day.

Oh, couldn't sleep. I think I'll go soak in the tub for a while.

Later

vharishankar · 03-09-2005, 09:44 PM

With Gentoo it's actually easier to set up these drivers and so on, although this particular issue is kernel related and distro-non-specific. I didn't have this much luck with Slackware and didn't get this far.

I even managed to get hardware accelerated 3d in Gentoo with the ATi drivers, something I couldn't set up with Slackware no matter how hard I tried.

Actually the Gentoo documentation is what made the difference. It's very logically organized, easy to follow and most importantly easy to understand. Once you understand what you're doing, this is the easiest distro in the world.

dalek · 03-10-2005, 03:14 AM

I have to agree. The install, though WELL documented, is the worst part of Gentoo. The only thing you have to watch is the etc-update. Other than that, Gentoo is a breeze.

It is pretty easy to update things. When I did my first install and I got a bootable kernel, I made sure to save that kernel while I was "refining" the newer kernels. I always kept that known to boot generic kernel so I could fall back to it when needed.

I have used Mandrake before and while Mandrake is easier to install, Gentoo is way easier to keep up to date.

Later