Re: IDE DMA disabled with via82cxxx on kernels >= 2.5.35

Andrew Morton (akpm@digeo.com)
Mon, 13 Jan 2003 19:47:08 -0800


On Mon January 13 2003 18:49, rwhron@earthlink.net wrote:
>
> 2.4.20-pre3-jam1:
>
> /dev/hda:
> Timing buffer-cache reads: 128 MB in 0.70 seconds =182.86 MB/sec
> Timing buffered disk reads: 64 MB in 2.07 seconds = 30.92 MB/sec
>
> 2.5.53-mm1
>
> /dev/hda:
> Timing buffer-cache reads: 128 MB in 7.20 seconds = 17.78 MB/sec
> Timing buffered disk reads: 64 MB in 19.66 seconds = 3.26 MB/sec

2.5.53-mm1 had a dud patch in it which made part of the kernel think HZ=100,
other parts think HZ=1000, depending on whether the .c file happened to
include config.h before including param.h.

Hence your nice 10x discrepancy.

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