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

[Andriy Gapon]

on 06/09/2010 16:23 Steven Hartland said the following:
> ----- Original Message ----- From: "Andriy Gapon" <avg at icyb.net.ua>
>>> 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.
> 
> Now monitoring these each minute to an rrd and text file and updated 8-STABLE
> with the following patches:
> http://people.freebsd.org/~mm/patches/zfs/v15/stable-8-v15.patch
> http://people.freebsd.org/~mm/patches/zfs/zfs_metaslab_v2.patch
> http://people.freebsd.org/~mm/patches/zfs/zfs_abe_stat_rrwlock.patch
> and then the needfree.patch I already posted.

Cool!

What about vm_paging_needed() patch?

-- 
Andriy Gapon