What are those changes for fixing the RAID0 performance?

Neil And RAIDers,

I have been looking for "what changes are made to fix/improve the parallel
access(?) to disks simultanously?".
I noticed as follow;

Up to Linux2.4.9  it got the same performance for RAID0(2-way stripe) and a
single disk(JBOD),
about 15 MB/sec with DMA on(hdparm -tT /dev/mdx).

On Linux 2.4.10 it improves to about 25 MB/sec for RAID0, 15 MB/sec for
single disk.
On Linux 2.4.18 it got the right performance; about 31 MB/sec for RAID0.

I tried to port the difference on /driver/ide and /drivers/md, but it did
not help.
I think there were changes on other functions to fix the parallel access(?)
to disks simultanously OR
to improve the RAID0 performance .

Why am I doing this kind of homework?

I can not migrate our linux to 2.4.18 so I want to port ONLY the fixes for
this performance
issue. I use Linux2.4.5.

Please help me if you know how I can work around.

Thanks in advance,

Bo