zfs very poor performance compared to ufs due to lack of cache?

[Andriy Gapon]

on 05/09/2010 16:19 Steven Hartland said the following:
>> ----- Original Message ----- From: "jhell" <jhell at DataIX.net>
>>>
>>> Attached is the needfree patch mentioned in the URL alongside a local
>>> system patch to adjust kern.maxusers to no more than 512 on systems that
>>> can support it...
> 
> No joy, still drops down to arc_min even with those two patches and changing
> to vm_paging_needed from the post Artem mentioned:
> http://lists.freebsd.org/pipermail/freebsd-hackers/2010-August/032731.html
> 
> So I suspect if I hadn't put in a high arc_min as well it would be back down
> at silly low levels.

But we don't really know this, do we?

I think that it would be useful for you and perhaps for us, if you'd set up
monitoring (and graphing) of key memory-related parameters.
E.g. at least the following sysctls:
kstat.zfs.misc.arcstats.size
vm.stats.vm.v_pdwakeups
vm.stats.vm.v_cache_count
vm.stats.vm.v_inactive_count
vm.stats.vm.v_active_count
vm.stats.vm.v_wire_count
vm.stats.vm.v_free_count

This would allow to see dynamics of memory consumption and correlation with
pagedaemon events.

-- 
Andriy Gapon