On Tue, Jun 28, 2005 at 12:02:55PM -0500, John A Meinel wrote:
>There has been discussion about changing the reading/writing code to be
>able to handle multiple pages at once, (using something like vread())
>but I don't know that it has been implemented.
that sounds promising
>Also, this would hurt cases where you can terminate as sequential scan
>early.
If you're doing a sequential scan of a 10G file in, say, 1M blocks I
don't think the performance difference of reading a couple of blocks
unnecessarily is going to matter.
>And if the OS is doing it's job right, it will already do some
>read-ahead for you.
The app should have a much better idea of whether it's doing a
sequential scan and won't be confused by concurrent activity. Even if
the OS does readahead perfectly, you'll still get a with with larger
blocks by cutting down on the syscalls.
Mike Stone