Bug 167726

Summary:	kernel patch for dma on ICH6_5 / 82801FB Mobile chipset
Product:	Gentoo Linux	Reporter:	Christopher Friedt <chrisfriedt>
Component:	[OLD] Core system	Assignee:	Gentoo Kernel Bug Wranglers and Kernel Maintainers <kernel>
Status:	VERIFIED NEEDINFO
Severity:	normal
Priority:	High
Version:	unspecified
Hardware:	x86
OS:	Linux
URL:	http://forums.gentoo.org/viewtopic-p-3911907.html#3911907
Whiteboard:
Package list:		Runtime testing required:	---

Description Christopher Friedt 2007-02-20 09:01:06 UTC

Hi Gentoo Kernel folks ;-)

I was wondering if you could push this patch upward in the kernel tree. It's for DMA on the ICH6_5 chipset from intel, which is found on some laptops. I'm using a Eurocom M560A.

I have been manually applying this patch since about March 2006 from kernels upward of 2.6.16. The problem was that I got this (garbage) laptop from work, immediately loaded gentoo on it, and noticed that everything from disk reads, to running X, or reading a CDROM was dreadfully slow - DMA of course ;-)

Then I did some research on the mainboard to see if there was something missing, tried running Ubuntu, and noticed that it lacked the slowness described above. I found this URL with a fairly anonymous patch and I guess up until now it hasn't sneaked into the kernel. 

http://marc.theaimsgroup.com/?l=linux-ide&m=114317385718285&w=2

This patch is extremely basic, and only adds a couple of new definitions which are supported by the existing kernel code. very harmless, but it increased my disk throughput by something like 3000% :)


Regards, 


~/Chris

Reproducible: Always

Steps to Reproduce:
1.you will need a laptop with ICH6_5 / 82801FB (Mobile chipset) from intel.
2. use any gentoo kernel as is
3. hdparm -tT <your root device>

Actual Results:  
something like 3MB/sec

Expected Results:  
32MB/sec

Check out the original patch at 

http://marc.theaimsgroup.com/?l=linux-ide&m=114317385718285&w=2

It has a bit more context which could be helpful.

Comment 1 Daniel Drake (RETIRED) gentoo-dev

2007-02-24 18:40:47 UTC

I think this is deliberately excluded because it supports the newer AHCI modes so you do not need to run it in blk_dev_piix legacy mode.

Try the ATA_PIIX driver. Note that your disk will move from hda to sda.

Comment 2 Daniel Drake (RETIRED) gentoo-dev

2007-03-10 04:47:45 UTC

see comment #1

Comment 3 Christopher Friedt 2007-03-10 11:39:20 UTC

I just tested it out - what was wierd was that with the old ATA_PIIX driver, the disks would still show up as /dev/hdc ... 

After changing to the newer driver, they are now /dev/sda ...

It's working very well now

Thanks for the help ;-)