Re: ide dma doesn't work
On Saturday 18 June 2005 05:29 pm, Glenn English wrote:
> I'm running a vanilla sarge install on a 2.8GHz P4, booting from a
> SCSI disk. There's a SATA disk and an IDE. The IDE disk is hda. The
> motherboard is an Intel 865.
>
> When writing a big file to hda, the CPU usage goes to 100% and stays
> there for a long time. And it takes a lot longer to write to hda than
> to the others. I interpret that to mean the system is doing
> programmed I/O instead of DMA.
>
> hdparm -i /dev/hda says udma5 (out of a possible 6) is the transfer
> mode.
>
> hdparm /dev/hda says
> "using_dma = 0 (off)"
>
> hdparm -d1 /dev/hda says
> "setting using_dma to 1 (on)
> HDIO_SET_DMA failed: Operation not permitted"
>
> I've looked at the kernel config and the modules and lsmod. As best I
> can tell all the IDE code is there -- that definitely doesn't mean it
> is. I've tried this with a Quantum 20G and a Maxtor 200G with exactly
> the same results (except the older drive does udma2, max).
>
> I googled and went through the tutorial at
>
> http://www.linuxdevcenter.com/pub/a/linux/2000/06/29/hdparm.html?page
>=1
>
> but got nothing like the I/O speed improvements shown there. I got
> only a 5 or 10 percent improvement.
>
> What am I not understanding?
I think the problem is with the order in which the IDE modules get
loaded., which afaik, it is an initrd/mkinitrd issue. Once Debian is
installed, I couldn't figure out how to change this order, compiled my
own kernel with the appropriate IDE driver compiled into the kernel.
There may be a better way but this will work if you are stuck.
BTW, this has been discussed on this list before so the archives will
have more info also.
--
Greg Madden
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