ZFS performance on 7.2-release/amd64 low compared to UFS2 + SoftUpdates

[Ronald Klop]

On Wed, 17 Jun 2009 09:34:02 +0200, Dan Naumov <dan.naumov at gmail.com>  
wrote:

> I am wondering if the numbers I am seeing is something expected or is
> something broken somewhere. Output of bonnie -s 1024:
>
> on UFS2 + SoftUpdates:
>
>               -------Sequential Output-------- ---Sequential Input--  
> --Random--
>               -Per Char- --Block--- -Rewrite-- -Per Char- --Block---  
> --Seeks---
> Machine    MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU   
> /sec %CPU
>          1024 56431 94.5 88407 38.9 77357 53.3 64042 98.6 644511 98.6
> 23603.8 243.3
>
> on ZFS:
>
>               -------Sequential Output-------- ---Sequential Input--  
> --Random--
>               -Per Char- --Block--- -Rewrite-- -Per Char- --Block---  
> --Seeks---
> Machine    MB K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU K/sec %CPU   
> /sec %CPU
>          1024 22591 53.7 45602 35.1 14770 13.2 45007 83.8 94595 28.0  
> 102.2  1.2
>
>
> atom# cat /boot/loader.conf
> vm.kmem_size="1024M"
> vm.kmem_size_max="1024M"
> vfs.zfs.arc_max="96M"

Isn't 96M for ARC really small?
Mine is 860M.
vfs.zfs.arc_max: 860072960
kstat.zfs.misc.arcstats.size: 657383376

I think the UFS2 cache is much bigger which makes a difference in your  
test.

Ronald.