Re: stochastic fair queueing in the elevator [Re: [BENCHMARK] 2.4.20-ck3 / aa / rmap with contest]

Andrea Arcangeli
2003-02-10T11:00:56Z

On Mon, Feb 10, 2003 at 09:40:34PM +1100, Nick Piggin wrote:
> I don't know too much about SCSI stuff, but if driver / wire / device
> overheads were that much higher at 128K compared to 512K I would
> think something is broken or maybe optimised badly.

I guess it's also a matter of the way the harddisk can serve the I/O if
it sees it all at the same time, not only the cpu/bus protocol after all
minor overhead. Most certainly it's not a software mistake in linux
that the big commands runs that much faster. Again go check the numbers
in bigbox.html between my tree, 2.4 and 2.5 in bonnie read sequential,
to see the difference between 128k commands and 512k commands with
reads, these are facts. (and no writes and no seeks here)

Andrea