Date: Wed, 31 Oct 2007 08:51:40 -0700 From: "Ali Mashtizadeh" <mashtizadeh@gmail.com> To: "Pawel Jakub Dawidek" <pjd@freebsd.org> Cc: Darren Reed <darrenr@freebsd.org>, freebsd-fs@freebsd.org, freebsd-current@freebsd.org, Dag-Erling Sm??rgrav <des@des.no> Subject: Re: ZFS kmem_map too small. Message-ID: <440b3e930710310851x27325d3ane5804c82bf8edd2c@mail.gmail.com> In-Reply-To: <20071009193051.GA13519@garage.freebsd.pl> References: <20071005000046.GC92272@garage.freebsd.pl> <20071008121523.GM2327@garage.freebsd.pl> <86bqb97mym.fsf@ds4.des.no> <20071008133846.GP2327@garage.freebsd.pl> <470BD649.9050505@freebsd.org> <20071009193051.GA13519@garage.freebsd.pl>
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For ZFS KVA_PAGES=512 seems to run very stable so it's unfortunate that we have to give up our VA space in the userland. I would personally like to see a move to a 4-4 Memory model or at least have it as a compile time option. Does anyone know if that's been attempted on FreeBSD? Ali On 10/9/07, Pawel Jakub Dawidek <pjd@freebsd.org> wrote: > > On Tue, Oct 09, 2007 at 12:28:09PM -0700, Darren Reed wrote: > > Pawel Jakub Dawidek wrote: > > >... > > > > > >For i386 one has to set, eg. 'options KVA_PAGES=512' to the kernel > > >config to be able to define kmem larger than ~700MB. I guess you're > > >running amd64, maybe there is similar requirement? > > > > > > > Given how much RAM PCs have these days, why isn't this a default for > > GENERIC? > > > > Or why isn't it at least a tunable rather than an option? > > This may be a good reason - today's PCs have a lot of RAM and KVA_PAGES > splits address space between userland and kernel - the more address > space for the kernel, the less address space for the userland. > KVA_PAGES=512 splits 4GB address space in half, so userland processes > can address at most 2GB of memory. > > -- > Pawel Jakub Dawidek http://www.wheel.pl > pjd@FreeBSD.org http://www.FreeBSD.org > FreeBSD committer Am I Evil? Yes, I Am! > > -- Ali Mashtizadeh علی مشتی زادهhelp
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