DMA problem with IDE hard disk

BB_DaKraxor · 10-17-2007, 08:21 PM

Hi,

I have Gentoo linux running fine. I used to use a SATA drive only but I had to attach an IDE one (80 GB Maxtor) recently and realized that it's very slow. I googled a lot and found out that I should have DMA enabled but I don't, so I tried to fix it, read dozens of posts with no luck yet.

Some additional info:

Code:

$ lspci | grep IDE
00:0f.0 IDE interface: VIA Technologies, Inc. VT8237A SATA 2-Port Controller (rev 80)
00:0f.1 IDE interface: VIA Technologies, Inc. VT82C586A/B/VT82C686/A/B/VT823x/A/C PIPC Bus Master IDE (rev 07)

Code:

$ grep "_VIA" /usr/src/linux/.config
# CONFIG_VIA_FIR is not set
CONFIG_BLK_DEV_VIA82CXXX=y
CONFIG_SATA_VIA=y
# CONFIG_PATA_VIA is not set
CONFIG_HW_RANDOM_VIA=y
# CONFIG_AGP_VIA is not set
# CONFIG_I2C_VIA is not set
# CONFIG_I2C_VIAPRO is not set
# CONFIG_SENSORS_VIA686A is not set
CONFIG_SND_VIA82XX=m
CONFIG_SND_VIA82XX_MODEM=m
CONFIG_SOUND_VIA82CXXX=m
# CONFIG_MIDI_VIA82CXXX is not set

Code:

a$ grep "_IDE" /usr/src/linux/.config
CONFIG_IDE=y
CONFIG_BLK_DEV_IDE=y
# CONFIG_BLK_DEV_IDE_SATA is not set
# CONFIG_BLK_DEV_HD_IDE is not set
CONFIG_BLK_DEV_IDEDISK=y
CONFIG_IDEDISK_MULTI_MODE=y
CONFIG_BLK_DEV_IDECD=y
# CONFIG_BLK_DEV_IDETAPE is not set
# CONFIG_BLK_DEV_IDEFLOPPY is not set
# CONFIG_BLK_DEV_IDESCSI is not set
# CONFIG_BLK_DEV_IDEACPI is not set
# CONFIG_IDE_TASK_IOCTL is not set
CONFIG_IDE_GENERIC=y
# CONFIG_BLK_DEV_IDEPNP is not set
CONFIG_BLK_DEV_IDEPCI=y
CONFIG_IDEPCI_SHARE_IRQ=y
CONFIG_BLK_DEV_IDEDMA_PCI=y
# CONFIG_BLK_DEV_IDEDMA_FORCED is not set
# CONFIG_IDEDMA_ONLYDISK is not set
# CONFIG_IDE_ARM is not set
CONFIG_BLK_DEV_IDEDMA=y
# CONFIG_IDEDMA_IVB is not set

When I try to enable DMA using hdparm, i get the following error:

Code:

a$ hdparm -d1 /dev/hdb

/dev/hdb:
 setting using_dma to 1 (on)
 HDIO_SET_DMA failed: Operation not permitted
 using_dma     =  0 (off)

DMA and some other (possibly related) things are recognized and enabled in my BIOS, I've checked that. I must be missing something. Does anyone know what the problem might be?

Thanks in advance.

BB_DaKraxor · 10-18-2007, 06:23 AM

... and nobody seems to have any idea.

saikee · 10-18-2007, 06:38 AM

I have never had a need to alter a Pata disk's DMA from 1Gb to 500Gb hard disks.

80Gb Pata should be have either ATA100 Mode 5 or 133ATA speed and in Mode 6. This information should appear in the Bios screen at boot time. There may be setting that you can override the Bios and using a 80-wire instead of a 40-wire IDE cable helps too, especially for the higher speed.

For a series of UDMA modes see this thread.

If you get a buffer read speed around 50Mb/s I would say it is normal, by root console command

Code:

hdparm -tT /dev/hda

assuming you are testing disk hda.

BB_DaKraxor · 10-18-2007, 12:13 PM

Thank you for your reply. I ran the test, the results are not satisfying:

Code:

$ sudo hdparm -tT /dev/hdb

/dev/hdb:
 Timing cached reads:   900 MB in  2.00 seconds = 449.78 MB/sec
 Timing buffered disk reads:   10 MB in  3.06 seconds =   3.26 MB/sec

There has to be a way to improve this speed.
I also get a 100% CPU usage whenever I access my IDE disk /dev/hdb and my system gets really slow.
It's quite annoying.

In the BIOS setup I found something like "UDMA mode 6" on the hard disk info screen, I think that means it's supported, I just need to enable it in my OS.

Am I right? Any ideas how to do that?

ghostdancer · 10-18-2007, 12:33 PM

Are you sure you are using the PATA module? Please check your SATA configuration in the kernel, there should be an option for VIA PATA support in there, remember to enable it.

jailbait · 10-18-2007, 12:44 PM

You may need a hardware converter:

http://cooldrives.stores.yahoo.net/s...e-adapter.html

--------------------
Steve Stites

BB_DaKraxor · 10-18-2007, 12:58 PM

Thanks for your help, the problem was that I didn't know I should have used the PATA module, I thought the IDE chipset driver is enough. After recompiling my kernel with CONFIG_PATA_VIA=y I get amazing test results:

Code:

$ sudo hdparm -tT /dev/hdb

/dev/hdb:
 Timing cached reads:   1612 MB in  2.00 seconds = 805.94 MB/sec
 Timing buffered disk reads:  130 MB in  3.02 seconds =  43.05 MB/sec

Thank you again!