FreeBSD and poor ata performance

[Kenneth Culver]

Quoting fandino <fandino at ng.fadesa.es>:

> Hello list,
>
>  This is an interesting issue. While I was installing  FreeBSD 5.3BETA7
> I wonder about the performance that the new branch will bring to my
> computer, and it was a deception how bad FreeBSD performs compared
> with Linux on the same hardware (even I repeat the test on different PC
> with identical results).
>
> A simple test is create one gibabyte file and later read this file again. To
> conduct an impartial test the disk (in UDMA5 mode), was formated in both
> operating systems with the native filesystem just to be sure that the
> physical position of the file will be the same in both tests.
>
> for linux it took about 23 seconds write the file and 18 read it.
>
> # time dd if=/dev/zero of=aa bs=1024k count=1024
> 1024+0 records in
> 1024+0 records out
>
> real    0m23.408s
> user    0m0.000s
> sys    0m4.470s
>
> # time dd if=aa of=/dev/null bs=1024k
> 1024+0 records in
> 1024+0 records out
>
> real    0m18.311s
> user    0m0.000s
> sys    0m5.850s
>
> and for FreeBSD it took 40 seconds write the file and 42 read it:
>
> # dd if=/dev/zero of=aa bs=1024k count=1024
> 1024+0 records in
> 1024+0 records out
> 1073741824 bytes transferred in 40.143630 secs (26747502 bytes/sec)
>
> # dd if=aa of=/dev/null bs=1024k
> 1024+0 records in
> 1024+0 records out
> 1073741824 bytes transferred in 42.711242 secs (25139560 bytes/sec)
>
> so as you can see linux was two times faster that FreeBSD :-?
> I would like to know if anyone knows  if this is normal or
> is a bug?
>
> thank you.
>

FreeBSD might be slower at using /dev/zero.... it might not be the ata
performance. I've never seen any problem with FreeBSD's ata performance on my
hardware.

Ken