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Date:      Mon, 06 Sep 2010 13:49:14 +0300
From:      Andriy Gapon <avg@icyb.net.ua>
To:        Steven Hartland <killing@multiplay.co.uk>
Cc:        freebsd-fs@freebsd.org, jhell <jhell@DataIX.net>
Subject:   Re: zfs very poor performance compared to ufs due to lack of cache?
Message-ID:  <4C84C72A.3020506@icyb.net.ua>
In-Reply-To: <1F64110BFBD5468B8B26879A9D8C94EF@multiplay.co.uk>
References:  <5DB6E7C798E44D33A05673F4B773405E@multiplay.co.uk><AANLkTi=6bta-Obrh2ejLCHENEbhV5stbMsvfek3Ki4ba@mail.gmail.com><4C825D65.3040004@DataIX.net>	<7EA7AD058C0143B2BF2471CC121C1687@multiplay.co.uk> <1F64110BFBD5468B8B26879A9D8C94EF@multiplay.co.uk>

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on 05/09/2010 16:19 Steven Hartland said the following:
>> ----- Original Message ----- From: "jhell" <jhell@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



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