SMP Strangeness

[Saul Thurrowgood]

I would have thought the filesystem has no effect on speed reported by
hdparm. Doesn't it just read from the raw device (/dev/sda)?

Anyway, does seem very slow. I get 40 MB/s on each IDE disk, they are
software striped to give about 72 MB/s.

Saul.

On Fri, 28 Jun 2002, Simon Fowler wrote:

> > BTW:
> > # hdparm -T -t /dev/sda
> >
> > /dev/sda:
> >  Timing buffer-cache reads:   128 MB in  0.79 seconds =162.03 MB/sec
> >  Timing buffered disk reads:  64 MB in  4.12 seconds = 15.53 MB/sec
>
> This last one is rather slow - my 7200rpm IDE disk gets 22-23MB/s
> off the platters, and I'd expect a good scsi disk to be a good bit
> faster . . .
> >
> >
> What filesystem are you using with this? ext3 is currently not at
> all well optimised for SMP, so if you're using that you may be
> seeing the results . . . Try mounting with ext2 instead, and see if
> that fixes things.
>
> Other than that, I can't think of anything right now, but you
> definitely shouldn't be seeing that kind of slowdown.
>
> Simon
>
>