On Mon, 18 Nov 2002, Olaf Meeuwissen wrote:
> I'm a minimalist and rolled my own kernel. It was absolutely bare
> bones and that had a noticable effect on hard disk performance. So I
> tinkered around a bit with kernel options and tested performance with
> hdparm -tT. Now I'd like to know what all those numbers mean and if
> they are reasonable (for my Dynabook SS S4/275PNHW).
>
> I've repeated all tests five times and dropped outliers. With my
> initial kernel I get
>
> ~110 MB/sec for buffer-cache reads
> ~ 2 MB/sec for buffered disk reads
>
> After tinkering I get
>
> ~ 55 MB/sec for buffer-cache reads
> ~ 14 MB/sec for buffered disk reads
>
> Question 1: Which of the two is "better" and why?
The second, because 2MB/second is PIO, while the second is DMA
transfers. So, buffer-cache reads may be slower... but not using 100%
CPU when you touch the hard disk is worth it. :)
> Question 2: Can I do better than this?
No.
> I still think hard disk performance is a bit slow but that may be just
> me.
It is. You have a laptop, which means a 5400RPM drive is *fast*. Don't
expect desktop performance out of these poor little drives. :)
One of the best ways to improve laptop performance is more memory
because, always, the hard drive performance is not going to be great.
Daniel
--
A man's worst difficulties begin when he is able to do as he likes.
-- Thomas Henry Huxley
