RE: problem with 2.6.13.[0-2]

[Parag Warudkar <kernel-stuff@comcast.net>]

> DMA is on in both 2.6.12.6 and in 2.6.13.2.  Here's what hdparm
> /dev/hda gives:
>
> in 2.6.12.6:
>
> /dev/hda:
>  multcount    = 16 (on)
>  IO_support   =  0 (default 16-bit)
>  unmaskirq    =  0 (off)
>  using_dma    =  1 (on)
>  keepsettings =  0 (off)
>  readonly     =  0 (off)
>  readahead    = 256 (on)
>  geometry     = 65535/16/63, sectors = 195371568, start = 0
>
> in 2.6.13.2 it's the same, except for
>
> multcount    =  0 (off)
>
> Could this be the problem, and if so, would setting multcount to on
> fix it? (I take it hdparm -m 16 /dev/hda would do it)

I doubt if multcount will make a difference, but you can try.
Probably next best thing to do is profile the slow kernel to find where it 
is spending time. (pass profile=2 on kernel command line and use 
readprofile or use oprofile).

Did you try hdparm -tT /dev/hda? It's going to be slow, thats for sure 
from what you described but try that and then post dmesg (for both 
kernels) and profile results - may be someone will get a clue from that.

Parag