Date: Thu, 25 Sep 2008 16:10:07 +0100 From: Pete French <petefrench@ticketswitch.com> To: admin@kkip.pl, koitsu@FreeBSD.org Cc: freebsd-stable@freebsd.org Subject: Re: vm.kmem_size settings doesn't affect loader? Message-ID: <E1KisTn-0000xy-AG@dilbert.ticketswitch.com> In-Reply-To: <20080925145154.GA15486@icarus.home.lan>
next in thread | previous in thread | raw e-mail | index | archive | help
> These are the tuning settings I use: > > vm.kmem_size="1536M" > vm.kmem_size_max="1536M" > vfs.zfs.arc_min="16M" > vfs.zfs.arc_max="64M" > > The entire copying process took almost 2 hours. Not once did I > experience kmem exhaustion. I can *guarantee* that I would have crashed > the box numerous times had I not tuned the machine with the values > above. I am interested in the last two values you have there - I also use ZFS and tune to prevent memory exhaustion. I tune kmem_size, but I have not bothered toi set the arc_min - and the default appears to be 16M anyway. The arc_max value I do set, but I got dreadful performance when I had it at 6M, so I upped it to 128M. This has not resulted in any panics, and gives much better performance. As I understand it there is only one ARC, and it comes from kernel space too, so setting it to an extra 64 meg should not use that much more memory, yes ? My setup is: vm.kmem_size="1024M" vm.kmem_size_max="1024M" vfs.zfs.arc_max="128M" vfs.zfs.prefetch_disable=1 This is on a 2gb amd64 machine, and works beautifully, with no out of memory errors and panics. I have been trying to panic this for a few days. I will probably chnage the kmem size to 1536 which is what I use on other machines though. -pete.
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?E1KisTn-0000xy-AG>