Date: Wed, 19 Nov 2008 02:13:46 -0800 From: Jeremy Chadwick <koitsu@FreeBSD.org> To: Nikolay Denev <ndenev@gmail.com> Cc: freebsd-current@freebsd.org, Larry Rosenman <ler@lerctr.org> Subject: Re: HEADS UP: New ZFS in the tree. Message-ID: <20081119101346.GA82818@icarus.home.lan> In-Reply-To: <FD98E80A-30DC-4700-9C0F-0D77835DBB32@gmail.com> 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> <FD98E80A-30DC-4700-9C0F-0D77835DBB32@gmail.com>
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On Wed, Nov 19, 2008 at 11:48:17AM +0200, Nikolay Denev wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > > 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 I've discussed ZFS tuning with another FreeBSD user 2-3 months ago. I lost 8 years worth of Email recently, so I can't go back and check who he was and what exactly was said. He was saying that under normal circumstances (in RELENG_7 and CURRENT), tuning should not really be necessary. He also pointed out that the way we're tuning things (specifically the variables we're using) are partially incorrect; some are unnecessary, such as arc_min. I'll see if I can find the mail on a mailing list (I think it was a public mail), but it'll take me some time. The information in the mail is very good, and should probably be pulled in to the ZFS Tuning wiki. Give me a while to find it. -- | Jeremy Chadwick jdc at parodius.com | | Parodius Networking http://www.parodius.com/ | | UNIX Systems Administrator Mountain View, CA, USA | | Making life hard for others since 1977. PGP: 4BD6C0CB |
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