More zfs benchmarks

[Jonathan Belson]

On 14 Feb 2010, at 20:26, Jonathan Belson wrote:

> On 14 Feb 2010, at 19:13, Artem Belevich wrote:
>> Can you check if kstat.zfs.misc.arcstats.memory_throttle_count sysctl
>> increments during your tests?
>> 
>> ZFS self-throttles writes if it thinks system is running low on
>> memory. Unfortunately on FreeBSD the 'free' list is a *very*
>> conservative indication of available memory so ZFS often starts
>> throttling before it's really needed. With only 2GB in the system,
>> that's probably what slows you down.
> 
> I tested a number of times during a 2GB write to a zfs partition and the count stayed at 0.

Oh, I should add that I use the following settings from the zfs tuning guide:

vm.kmem_size="1024M"
vm.kmem_size_max="1024M"
vfs.zfs.arc_max="100M"

Cheers,

--Jon