slow tar performance on fbsd5

[JG]

> Will noatime make a difference when unpacking a tar archive (assuming an
> otherwise idle system, at least)?  My understanding of atime is that it
> might slow down the disk for later accesses due to atime writes, but
> when creating files it shouldn't have any effect.  Is that not correct?

Yes, you're right.

> Your other settings appear ok, but I'd turn off hyperthreading.  Almost
> every FreeBSD/HT test has shown that it reduces performance because the
> scheduler is not HT-aware.  When the system is relatively idle (single
> dd running, for example), it might not pessimize things, but it will
> most likely slow you down under load.

HTT is a big performance hit for me, mainly for webserver. I've much worse diskinfo
results without HTT, don't know why. Tar is upacking a bit longer with HTT disabled.

> This sounds like you're running into the old "lemming syncer" problem.
> There is currently some work on disk schedulers (even a Summer of Code
> project), but it will most likely not make it into 5.x.

Agrh..

Regards,
Jarek