Enabling DMA through boot loader (grub)

bxb32001 · 10-28-2003, 10:08 PM

Hi everyone,

I perused the forum (and google) on how to improve the performance of my Red Hat 9 system and I the tip I noticed the most was improving hard drive performance.

I did some more digging...

From what I gather the easiest way to enable DMA is to append the boot loader config file (please tell me if I am mistaken).

The sample I found was meant for lilo.conf and the conf file was meant to be appended with

Quote:

append = “ide0=dma”

Is that supposed to be with or without the 'append'?

Anyway, I guess the actual question would be, how do I do it in GRUB?

Do I just add the same line?

grub.conf typically looks like this:

Quote:

default=0
timeout=10
splashimage=(hd0,0)/grub/splash.xpm.gz

# section to load linux
title Red Hat Linux (2.4.18-5.47)
root (hd0,0)
kernel /vmlinuz-2.4.18-5.47 ro root=/dev/sda2
initrd /initrd-2.4.18-5.47.img

# section to load Windows 2000
title windows
rootnoverify (hd0,0)
chainloader +1

Where should I put the line that tells GRUB to enable DMA for my HDD?

Thanks in advance

- Bryan

edit... I am not sure if this post is appropriate for this forum... if the moderators deem it is not please transfer it to where it is most appropriate, I apologize and thank you.

undeadpenguin · 10-28-2003, 10:34 PM

Put it at the top, the 'append' is needed.

bxb32001 · 10-28-2003, 10:52 PM

Thanks for the quick reply... and, of course, for your help...

It's just me of course, but when solutions are as simple as this I tend to think it can't be that simple... I must have missed something or done something wrong...

So my apologies if I follow up with this question...

does this truly help (improve performance)?

synaptical · 10-28-2003, 11:06 PM

test before and after using hdparm:

# hdparm -Tt /dev/hdx

and compare the results.

bxb32001 · 10-28-2003, 11:35 PM

I shall... thanks...

bxb32001 · 10-29-2003, 05:43 AM

Okay... I'm finally home and I just booted my linux box...

Typed in 'hdparm /dev/hda' and got this:

Quote:

[root@mybox me]# /sbin/hdparm /dev/hda

/dev/hda:
multcount = 16 (on)
IO_support = 0 (default 16-bit)
unmaskirq = 0 (off)
using_dma = 1 (on)
keepsettings = 0 (off)
readonly = 0 (off)
readahead = 8 (on)
geometry = 9729/255/63, sectors = 156301488, start = 0

Huh? DMA is already on... does this mean I don't have to do anything? That it's already enabled?

synaptical · 10-29-2003, 12:01 PM

it sure looks like it's already on. why don't you run the benchmark and post your results. you should probably get disk read numbers somewhere at least above the 30 range if it's enabled (depending on your hardware, of course). if it comes back something like 2.xx or 3.xx, it's not enabled.