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Date:      Wed, 19 Nov 2008 11:48:17 +0200
From:      Nikolay Denev <ndenev@gmail.com>
To:        Larry Rosenman <ler@lerctr.org>
Cc:        Jeremy Chadwick <koitsu@FreeBSD.org>, freebsd-current@freebsd.org
Subject:   Re: HEADS UP: New ZFS in the tree.
Message-ID:  <FD98E80A-30DC-4700-9C0F-0D77835DBB32@gmail.com>
In-Reply-To: <alpine.BSF.2.00.0811190323110.59299@borg>
References:  <20081117205526.GC1733@garage.freebsd.pl> <8ECD400F-BFE3-4E31-94F0-39AF5F44FDAC@gmail.com> <20081119090307.GA81236@icarus.home.lan> <alpine.BSF.2.00.0811190323110.59299@borg>

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On 19 Nov, 2008, at 11:25 , Larry Rosenman wrote:

> On Wed, 19 Nov 2008, Jeremy Chadwick wrote:
>
>>
>> Since this is CURRENT, you should be able to increase the kmem_size
>> and kmem_size_max entries to something larger than 1536M, especially
>> since the box has 4GB of RAM.  (You shouldn't do this on RELENG_7).
>>
>> You might also consider disabling prefetch; there are reports of
>> peoples' boxes locking up hard (requiring a hard reset) when prefetch
>> is enabled.  Others (like myself) just see "better overall system
>> responsiveness" when prefetch is disabled.
> Just as a note, with a -CURRENT from shortly after the ZFS upgrade,  
> the vm.kmem* tuneables, without ANY override on my 4G amd64 box:
>
> vm.kmem_size_scale: 3
> vm.kmem_size_max: 4509713203
> vm.kmem_size_min: 0
> vm.kmem_size: 1381195776
>
> this is with a 2T zfs array, if that matters.
>
>
> -- 
> Larry Rosenman                     http://www.lerctr.org/~ler
> Phone: +1 512-248-2683                 E-Mail: ler@lerctr.org
> US Mail: 430 Valona Loop, Round Rock, TX 78681-3893

Well, it looks like that on -current and a 4G amd64 machine probably  
there is no need
to tune anything. Here are my defaults with everything vm and zfs  
related in loader.conf commented :

vm.kmem_size_max: 4509713203
vfs.zfs.arc_max: 863907840


- --
Regards,
Nikolay Denev




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