> While optimizing the program I discovered that disk I/O
> performance in Linux could be improved substantially. In
> particular, there are two main problems:
>
> 1) The kernel copies data many times before it ends up in user
> space.
I'm very sorry, but you seem to be too late. This problem is
(at least partially) fixed in the newer 2.3 kernels...
> 2) Using mmap doesn't help because it serializes I/O within a single
> process (you can't read simultaneously from two disks).
A single process uses a single thread of control, and yes,
we do readahead over RAID0 sets...
If you want to do true async I/O, you can just use the
interface glibc gives you to do that.
Rik -- Open Source: you deserve to be in control of your data.
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