Date: Sun, 28 Jun 2009 19:41:14 -0500 From: Alan Cox <alan.l.cox@gmail.com> To: Nathanael Hoyle <nhoyle@hoyletech.com> Cc: Wojciech Puchar <wojtek@wojtek.tensor.gdynia.pl>, freebsd-hackers@freebsd.org Subject: Re: large pages (amd64) Message-ID: <ca3526250906281741h5c6c9407vdf9ea849330023ed@mail.gmail.com> In-Reply-To: <4A480760.50705@hoyletech.com> References: <alpine.BSF.2.00.0906281933580.1809@wojtek.tensor.gdynia.pl> <4A480760.50705@hoyletech.com>
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On Sun, Jun 28, 2009 at 7:14 PM, Nathanael Hoyle <nhoyle@hoyletech.com>wrote: > Wojciech Puchar wrote: > >> i enabled >> vm.pmap.pg_ps_enabled: 1 >> >> >> could you please explain what exactly this values means? >> because i don't understand why promotions-demotions!=mappings >> >> vm.pmap.pde.promotions: 2703 >> vm.pmap.pde.p_failures: 6290 >> vm.pmap.pde.mappings: 610 >> vm.pmap.pde.demotions: 289 >> >> >> >> >> other question - tried enabling it on my i386 laptop (256 megs ram), >> always mappings==0, while promitions>demotions>0. >> >> certainly there are apps that could be put on big pages, gimp editing 40MB >> bitmap for example >> > > Just to be clear, since you say i386 (I presume you mean architecture), I > believe the Physical Address Extensions which allowed 2MB Page Size bit to > be set was introduced with Pentium Pro. Processors prior to this were > limited to standard 4KB pages. > No. Many of those processors supported 4MB pages. Regards, Alan
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