Date: Thu, 16 Aug 2012 20:15:48 -0700 From: Marie Bacuno II <gezeala@gmail.com> To: Garrett Cooper <yanegomi@gmail.com> Cc: "freebsd-performance@freebsd.org" <freebsd-performance@freebsd.org> Subject: Re: vm.kmem_size_max and vm.kmem_size capped at 329853485875 (~307GB) Message-ID: <B74BE4AB-AB67-45BD-BFC3-9AE33A85751C@gmail.com> In-Reply-To: <CAGH67wTNfW45pgJ_%2BVn_sX%2BP9M5B5wzPT9270dRmWjYF6KerrA@mail.gmail.com> References: <CAJKO3mU8bfn=jmWNSpvAXOR1AWyAAM0Sio1D1PnOYg8P59V9cg@mail.gmail.com> <CAGH67wS=jue7%2B92jSCyaydOLHC=hPwtndV64FVtC7nhDsPvFng@mail.gmail.com> <CAGH67wTNfW45pgJ_%2BVn_sX%2BP9M5B5wzPT9270dRmWjYF6KerrA@mail.gmail.com>
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On Aug 16, 2012, at 18:47, Garrett Cooper <yanegomi@gmail.com> wrote: > On Thu, Aug 16, 2012 at 6:44 PM, Garrett Cooper <yanegomi@gmail.com> wrote= : >> On Thu, Aug 16, 2012 at 5:46 PM, Gezeala M. Bacu=C3=B1o II <gezeala@gmail= .com> wrote: >>> Hello fellow listers, >>>=20 >>> On a server with 512GB RAM it appears that vm.kmem_size_max is not >>> being auto-tuned to use >329853485875 (~307GB). >>>=20 >>> On this machine vm.kmem_size is equal to vm.kmem_size_max >>>=20 >>> # from sysctl >>> vm.kmem_size_max: 329853485875 >>> vm.kmem_size: 329853485875 >>>=20 >>> 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. >>>=20 >>> 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: >>>=20 >>> OK set vm.kmem_size_max=3D"300G" >>> OK boot >>>=20 >>> On all PCBSD (8,9) or FreeBSD (8.1,8.2,9) machines we have, >>> vm.kmem_size_max is always set to 329853485875. >>>=20 >>> 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. >>>=20 >>> I'm browsing thru the source code at >>> http://fxr.watson.org/fxr/search?v=3DFREEBSD9&string=3Dvm.kmem_size_max >>> and I'm still trying to make sense of how vm.kmem_size_max is >>> computed. >>>=20 >>> I have posted the same topic on forums.freebsd.org but I'm not getting >>> any recommendations. >>>=20 >>> Please see the link for additional details: >>> http://forums.freebsd.org/showthread.php?t=3D33977 >>=20 >> Have you tried defining VM_KMEM_SIZE_MAX to your target value? >>=20 >> Its architecture specific BTW... see >> sys/<architecture>/include/vmparam.h -- look for `VM_KMEM_SIZE_MAX`. >=20 > Also, it's a tunable, not a sysctl... so you need to set the value in > /boot/loader.conf . > -Garrett Thanks for the quick reply. Yes, had it set on /boot/loader.conf and by trial and error on the loader pr= ompt. We were able to bump it to 400G successfully. Tried 500G and 450G and the ma= chine just spews out garbage in the screen. The latest output from "zfs-stats -a" with vm.kmem_size_max=3D"400G" is in t= he forum: http://forums.freebsd.org/showthread.php?t=3D33977 About the code, I am looking into amd64 arch. Still checking the values of t= he variables.. Can't just retrieve them using getconf. If you can point me t= o a doxygen like documentation appreciate it a lot. Where does the constant value 329853485875 came from? Thanks!
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