Date: Sun, 20 May 2012 02:25:59 -0500 From: Alan Cox <alan.l.cox@gmail.com> To: Marko Zec <zec@fer.hr> Cc: freebsd-hackers@freebsd.org, freebsd-amd64@freebsd.org Subject: Re: superpages and kmem on amd64 Message-ID: <CAJUyCcOWRKw5=NH_WrkKVcOMqGy2f3HroBX=pGbcbS3UbUZkxg@mail.gmail.com> In-Reply-To: <201205200901.32613.zec@fer.hr> References: <201205200901.32613.zec@fer.hr>
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On Sun, May 20, 2012 at 2:01 AM, Marko Zec <zec@fer.hr> wrote: > Hi all, > > I'm playing with an algorithm which makes use of large contiguous blocks of > kernel memory (ranging from 1M to 1G in size), so it would be nice if those > could be somehow forcibly mapped to superpages. I was hoping that the VM > system would automagically map (merge) contiguous 4k pages to superpages, > but > apparently it doesn't: > > vm.pmap.pdpe.demotions: 2 > vm.pmap.pde.promotions: 543 > vm.pmap.pde.p_failures: 266253 > vm.pmap.pde.mappings: 0 > vm.pmap.pde.demotions: 31 > > No, your conclusion is incorrect. These counts show that 543 superpage mappings were created by promotion. Alan
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