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

[Steven Hartland]

----- 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.

    Regards
    Steve

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