[lug] RH Linux download + hdparm

[John Karns]

On Wed, 17 Oct 2001, Bonnell, Doug said:

> DMA and multicount will increase performance (but only
> if you have DMA!).
>
> My 266Mhz PII has multicount = 16 and DMA = 1.
>
>     hdparm -t /dev/hda shows 12.65 Mbytes/second

On my Dell Inspiron 700Mhz w/ IBM Travelstar hdd, adding multicount
doesn't seem to have an effect.  I suspect this varies between
controllers, hdd's and kernel version.  My kernel supports DMA via the
generic IDE DMA rather than specifically for the chip.

I wonder if chip specific support would increase performance.

w/ DMA                     -> 15.8 MB/s

w/ DMA + multicount = 16   -> 16 MB/s

no DMA, w/ multicount = 16 -> 4.0 MB/s

no DMA, no multicount      -> 3.5 MB/s


Also, it's worth noting from "man hdparm" that:

"... most/all modern IDE drives default to their fastest PIO transfer
mode at power-on."


----------------------------------------------------------------
John Karns                                        jkarns at csd.net