Date: Thu, 16 Aug 2012 17:46:58 -0700 From: =?ISO-8859-1?Q?Gezeala_M=2E_Bacu=F1o_II?= <gezeala@gmail.com> To: freebsd-performance@freebsd.org Subject: vm.kmem_size_max and vm.kmem_size capped at 329853485875 (~307GB) Message-ID: <CAJKO3mU8bfn=jmWNSpvAXOR1AWyAAM0Sio1D1PnOYg8P59V9cg@mail.gmail.com>
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Hello fellow listers, On a server with 512GB RAM it appears that vm.kmem_size_max is not being auto-tuned to use >329853485875 (~307GB). On this machine vm.kmem_size is equal to vm.kmem_size_max # from sysctl vm.kmem_size_max: 329853485875 vm.kmem_size: 329853485875 On a machine with 1GB of RAM, I have successfully set vm.kmem_size_max to 330GB and vm.kmem_size automatically adjusts to 1GB even if I manually set it in /boot/loader.conf. But on the machine with 512GB of RAM it just resets. For the machine to boot, we need to go to the loader prompt and issue: OK set vm.kmem_size_max="300G" OK boot On all PCBSD (8,9) or FreeBSD (8.1,8.2,9) machines we have, vm.kmem_size_max is always set to 329853485875. How can I increase vm.kmem_size_max to use at least 500GB? And how is 329853485875 determined (formula)? I need to increase vm.kmem_size_max and vm.kmem_size so I can set vfs.zfs.arc_max (ZFS ARC) to use say 490GB. I'm browsing thru the source code at http://fxr.watson.org/fxr/search?v=FREEBSD9&string=vm.kmem_size_max and I'm still trying to make sense of how vm.kmem_size_max is computed. I have posted the same topic on forums.freebsd.org but I'm not getting any recommendations. Please see the link for additional details: http://forums.freebsd.org/showthread.php?t=33977 TIA! -- regards
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