2.2 kernels and IDE disk access

[Jerry Feldman {75562}]

I discovered yesterday that the 2.2 kernels are set up not to use DMA to
drive your disks by default. When I upgrade, one of the first things I do is
to customize the kernel. There are several performance issues. One is to
compile as a Pentium II. Another is to use hardware floating point rather
than software emulation. I had some disk problems over the weekend (not
Linux related), and I discussed them with my office mate. He mentioned the
DMA issue. I first looked at the boot log, which didn't raise any flags. I
then looked at the kernel config, and found a flag "Use DMA by default" in
the block drivers section. 
My wording might a bit off. Turning this flag on causes the kernel to use
DMA by default. When looking at the boot log, you should see DMA or UDMA
adjacent to the drives. I think this applies only to IDE. I think SCSI uses
DMA by default. 
-- 
Jerry Feldman (HP On-Site Consultant) http://gbrweb.msd.ray.com/~gzf/
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