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Date:      Mon, 06 Sep 2010 09:39:39 -0400
From:      jhell <jhell@DataIX.net>
To:        Andriy Gapon <avg@icyb.net.ua>
Cc:        freebsd-fs@freebsd.org
Subject:   Re: zfs very poor performance compared to ufs due to lack of cache?
Message-ID:  <4C84EF1B.5040004@DataIX.net>
In-Reply-To: <4C84EBFE.7030408@icyb.net.ua>
References:  <5DB6E7C798E44D33A05673F4B773405E@multiplay.co.uk><AANLkTi=6bta-Obrh2ejLCHENEbhV5stbMsvfek3Ki4ba@mail.gmail.com><4C825D65.3040004@DataIX.net>	<7EA7AD058C0143B2BF2471CC121C1687@multiplay.co.uk> <1F64110BFBD5468B8B26879A9D8C94EF@multiplay.co.uk> <4C84C72A.3020506@icyb.net.ua> <C8FDED84AE204EB3B143C3F8301E58E3@multiplay.co.uk> <4C84EBFE.7030408@icyb.net.ua>

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On 09/06/2010 09:26, Andriy Gapon wrote:
> on 06/09/2010 16:23 Steven Hartland said the following:
>> ----- Original Message ----- From: "Andriy Gapon" <avg@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?
> 

Ugh! I keep forgetting about this one! and confusing it for the needfree
change. /Ugh!

It is attached as well.

-- 

 jhell,v

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diff -r 1f75c636f0d4 sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c
--- a/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c	Mon Sep 06 09:32:32 2010 -0400
+++ b/sys/cddl/contrib/opensolaris/uts/common/fs/zfs/arc.c	Mon Sep 06 09:36:57 2010 -0400
@@ -2164,7 +2164,7 @@
 	 * If pages are needed or we're within 2048 pages
 	 * of needing to page need to reclaim
 	 */
-	if (vm_pages_needed || (vm_paging_target() > -2048))
+	if (vm_paging_needed())
 		return (1);
 
 #if 0

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