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Date:      Sun, 23 Sep 2007 15:35:46 -0700
From:      Darren Reed <darrenr@freebsd.org>
To:        Larry Rosenman <ler@lerctr.org>
Cc:        freebsd-current@freebsd.org, Claus Guttesen <kometen@gmail.com>
Subject:   Re: panic: kmem_malloc(131072): kmem_map too small (AMD64)
Message-ID:  <46F6EA42.1070401@freebsd.org>
In-Reply-To: <20070923161722.B41582@thebighonker.lerctr.org>
References:  <20070921102946.T11189@borg> <46F415BF.9010500@FreeBSD.org>	<20070921140550.D96923@thebighonker.lerctr.org>	<46F41CFF.6080108@FreeBSD.org> <46F58799.1030702@freebsd.org>	<b41c75520709230137u669da1ddy7819ed1872af01b7@mail.gmail.com> <20070923161722.B41582@thebighonker.lerctr.org>

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Larry Rosenman wrote:
> On Sun, 23 Sep 2007, Claus Guttesen wrote:
>
>>> So I just received this courtesy of ZFS:
>>> panic: kmem_malloc(131072): kmem_map too small: 343027712 total 
>>> allocated
>>> cpuid = 0
>>> KDB: enter: panic
>>>
>>> This was with these settings in loader.conf:
>>> vm.kmem_size=419430400
>>> vm.kmem_size_max=419430400
>>> vfs.zfs.arc_max=409715200
>>
>> How much ram do you have? Is this amd64 or i386?
>
> In my case, 4Gig ram, amd64, and I've seen the panic even with
> 750M vm.kmem_size.
>
> Do we have guidelines on what vm.kmem_size(|_max) should be set to?

My advice would be to tune the ZFS ARC to be smaller than kmem_size.
The above represents a mistake in sizing the ARC.
When using ZFS, I'd tune vm.kmem_size to be as much as 80% of RAM,
unless you're running *large* applications in user space.

Darren




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