Enable DMA on hard drives

thorax · 06-10-2004, 05:08 PM

Hi!
After I copied some huge amounts of data from one hard disk to another (and the system becoming unusable meanwhile) it came to my mind that DMA could be disabled for my hard drives. A simple 'hdparm /dev/hda' and I was sure. But enabling DMA with 'hdparm -d1 /dev/hda' just says 'Operation not permitted.' But I was trying as root, so I tried a chmod 777 /dev/hda and chown 777 /dev/hda. But it didn't had any effects.
Does anyone know a way to enable DMA? I use the 2.6.7-rc3 Kernel and an nForce2 chipset. The FAQ on nvidia's homepage just tells you to use the universal ide driver, since the nForce2 IDE controller should be standard-compliant.

320mb · 06-10-2004, 05:14 PM

what do you get when you type this in

Code:

hdparm -i /dev/hda

vinay_s_s · 06-10-2004, 05:29 PM

chown 777 /dev/hda ???
whats that ?
i think it has to be: chown root /dev/hda

now try hdparm -d1 /dev/hda

thorax · 06-10-2004, 05:54 PM

Quote:

Originally posted by 320mb
what do you get when you type this in

Code:

hdparm -i /dev/hda

I get this:

Code:

 Model=WDC WD800BB-75DKA0, FwRev=77.07W77, SerialNo=WD-WMAHL3118939
 Config={ HardSect NotMFM HdSw>15uSec SpinMotCtl Fixed DTR>5Mbs FmtGapReq }
 RawCHS=16383/16/63, TrkSize=57600, SectSize=600, ECCbytes=74
 BuffType=DualPortCache, BuffSize=2048kB, MaxMultSect=16, MultSect=16
 CurCHS=16383/16/63, CurSects=16514064, LBA=yes, LBAsects=156250000
 IORDY=on/off, tPIO={min:120,w/IORDY:120}, tDMA={min:120,rec:120}
 PIO modes: pio0 pio1 pio2 pio3 pio4
 DMA modes: mdma0 mdma1 mdma2 udma0 udma1 udma2 udma3 udma4 *udma5
 AdvancedPM=no WriteCache=enabled
 Drive Supports : Reserved : ATA-1 ATA-2 ATA-3 ATA-4 ATA-5 ATA-6

chmod 777 means, giving read, write, execution rights to all users.

vinay_s_s · 06-10-2004, 07:52 PM

thorax, u had done "chown 777 " (not chmod) (see original post!!)

according to the info:
DMA modes: mdma0 mdma1 mdma2 udma0 udma1 udma2 udma3 udma4 *udma5

Its already on the DMA mode!! (UDMA5)

thorax · 06-11-2004, 06:16 AM

As you can see, it's not:

Code:

/dev/hda:
 multcount    = 16 (on)
 I/O support  =  0 (default 16-bit)
 unmaskirq    =  0 (off)
 using_dma    =  0 (off)  <-------
 keepsettings =  0 (off)
 nowerr       =  0 (off)
 readonly     =  0 (off)
 readahead    = 256 (on)
 geometry     = 16383/255/63, sectors = 156250000, start = 0
 busstate     =  1 (on)

And, why should I have a transfer rate of ~4 MiB/s when DMA is enabled?

btw, I tried your 'chown root /dev/hda', and it didn't work, too.

When I try to execute 'hdparm -d1 /dev/hda' I get the following:

Code:

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

thorax · 06-11-2004, 06:26 AM

btw, does this include any infos if my chipset supports dma under Linux?

Code:

BIOS-provided physical RAM map:
Shuttle AN35N detected: BIOS IRQ0 pin2 override will be ignored
ACPI: BIOS IRQ0 pin2 override ignored.
CPU:     After generic identify, caps: 0383fbff c1c3fbff 00000000 00000000
CPU:     After vendor identify, caps: 0383fbff c1c3fbff 00000000 00000000
ide: Assuming 33MHz system bus speed for PIO modes; override with idebus=xx
ide0 at 0x1f0-0x1f7,0x3f6 on irq 14
ide1 at 0x170-0x177,0x376 on irq 15

It was part of my dmesg.

My Kernel .config inclueds the following, so dma should work (?)

Code:

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

the nVidia nForce Linux drivers FAQ just says:

Quote:

Q: My IDE hard drive is running very slowly, how can I enable DMA mode?

A: A kernel patch was added in kernel 2.4.21pre3-ac1 which enables DMA for the nForce2 IDE controller and should be available in the final released 2.4.21 kernel. An alternative to upgrading your kernel is to use the "hdparm" utility to enable DMA for your hard drive. For example:

example% su
Password: ******
example# hdparm -d 1 /dev/hdX

Where /dev/hdX is the IDE device you wish to enable DMA for. You must do this every time you reboot, or add it to an rc script. Some distributions have a file "/etc/sysconfig/harddisks" where you can enable this for all hard drives on system boot.

When the dma patch was added in a 2.4 Kernel, it should surely be available in my 2.6 Kernel, right?