Date: Mon, 18 Aug 2003 17:11:03 -0400 (EDT) From: Jeff Roberson <jroberson@chesapeake.net> To: "Alan L. Cox" <alc@imimic.com> Cc: cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/i386/i386 pmap.c Message-ID: <20030818171003.Y12093-100000@mail.chesapeake.net> In-Reply-To: <20030818165803.P12093-100000@mail.chesapeake.net>
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On Mon, 18 Aug 2003, Jeff Roberson wrote: > On Mon, 18 Aug 2003, Alan L. Cox wrote: > > > Jeff Roberson wrote: > > > > > > On Sun, 17 Aug 2003, Alan Cox wrote: > > > > > > > alc 2003/08/17 15:27:30 PDT > > > > > > > > FreeBSD src repository > > > > > > > > Modified files: > > > > sys/i386/i386 pmap.c > > > > Log: > > > > Acquire the pte object's mutex when performing vm_page_grab(). Note: It is > > > > my long-term objective to eliminate the pte object. In the near term, this > > > > does, however, enable the addition of some vm object locking assertions. > > > > > > > > Revision Changes Path > > > > 1.427 +4 -0 src/sys/i386/i386/pmap.c > > > > > > > > > > What is your plan for the pte object? Will we still be able to page out > > > page tables? > > > > > > > Yes, expect no loss of functionality. The use of a pte object simply > > reflects the pre-"VM_ALLOC_NOOBJ" days when vm_page_alloc() always > > required an object to contain the allocated page. As some of my other > > recent pmap changes have demonstrated it's equally easy and perhaps > > faster to use the page table structure itself as the "container" rather > > than doing vm_page_lookup() on the pte obj. (Annecdotal tests suggested > > that eliminating the vm_page_lookup()s from places such as pmap_copy() > > reduced "buildworld" time by ~0.5%.) > > > > Regards, > > Alan > > > > I thought that the pte object was required so that we could page out the > page tables though? Will the pager still know that it can discard the > pages? We should be able to recreate them from a fault, yes? Do you > intend to modify the pager so that it will simply discard unwired NOOBJ > pages? It seems like that would work. > > Thanks, > Jeff > Nevermind, I misunderstood. According to jake, we only discard page tables once we discard all of the pages that they map. The rest of the time the page table pages are wired.home | help
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