Re: [RFC, PATCHv1 00/28] 5-level paging

From	Andi Kleen <ak@linux.intel.com>
Newsgroups	linux.kernel
Subject	Re: [RFC, PATCHv1 00/28] 5-level paging
Date	2016-12-09 17:50 +0100
Message-ID	<sMwwW-5CD-19@gated-at.bofh.it> (permalink)
References	<sM9K2-8la-5@gated-at.bofh.it> <sMlBw-7ym-5@gated-at.bofh.it> <sMqKS-27A-29@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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> On other hand, large virtual address space would put more pressure on
> cache -- at least one more page table per process, if we make 56-bit VA
> default.

The top level page always has to be there unless you disable it at boot time
(unless you go for a scheme where some processes share top level pages, and
others do not, which would likely be very complicated)

But even with that it is more than one: A typical set up has at least two extra
4K pages overhead, one for the bottom and one for the top mappings. Could easily be
more.

-Andi

Thread

[RFC, PATCHv1 00/28] 5-level paging "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-12-08 17:30 +0100
  [RFC, PATCHv1 24/28] x86/mm: add sync_global_pgds() for configuration with 5-level paging "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-12-08 17:30 +0100
    Re: [RFC, PATCHv1 24/28] x86/mm: add sync_global_pgds() for  configuration with 5-level paging Andy Lutomirski <luto@amacapital.net> - 2016-12-08 19:50 +0100
      Re: [RFC, PATCHv1 24/28] x86/mm: add sync_global_pgds() for  configuration with 5-level paging "Kirill A. Shutemov" <kirill@shutemov.name> - 2016-12-08 20:40 +0100
  [RFC, PATCHv1 19/28] x86/mm: basic defines/helpers for CONFIG_X86_5LEVEL "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-12-08 17:30 +0100
  [RFC, PATCHv1 04/28] asm-generic: introduce <asm-generic/pgtable-nop4d.h> "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-12-08 17:30 +0100
  [RFC, PATCHv1 17/28] x86/mm: define virtual memory map for 5-level paging "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-12-08 17:30 +0100
    Re: [RFC, PATCHv1 17/28] x86/mm: define virtual memory map for  5-level paging Randy Dunlap <rdunlap@infradead.org> - 2016-12-08 20:00 +0100
      Re: [RFC, PATCHv1 17/28] x86/mm: define virtual memory map for  5-level paging "Kirill A. Shutemov" <kirill@shutemov.name> - 2016-12-08 20:30 +0100
  [RFC, PATCHv1 27/28] x86: enable la57 support "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-12-08 17:30 +0100
  [QEMU, PATCH] x86: implement la57 paging mode "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-12-08 17:30 +0100
    Re: [Qemu-devel] [QEMU, PATCH] x86: implement la57 paging mode no-reply@patchew.org - 2016-12-08 17:50 +0100
  [RFC, PATCHv1 28/28] TESTING-ONLY: bump TASK_SIZE_MAX "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-12-08 17:30 +0100
  [RFC, PATCHv1 03/28] arch, mm: convert all architectures to use 5level-fixup.h "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-12-08 17:30 +0100
  [RFC, PATCHv1 18/28] x86/paravirt: make paravirt code support 5-level paging "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-12-08 17:30 +0100
  [RFC, PATCHv1 07/28] x86: trivial portion of 5-level paging conversion "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-12-08 17:30 +0100
  [RFC, PATCHv1 01/28] asm-generic: introduce 5level-fixup.h "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-12-08 17:30 +0100
  [RFC, PATCHv1 26/28] x86/mm: add support for 5-level paging for KASLR "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-12-08 17:30 +0100
  [RFC, PATCHv1 06/28] x86: basic changes into headers for 5-level paging "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-12-08 17:40 +0100
  [RFC, PATCHv1 02/28] asm-generic: introduce __ARCH_USE_5LEVEL_HACK "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2016-12-08 17:40 +0100
  Re: [RFC, PATCHv1 00/28] 5-level paging Linus Torvalds <torvalds@linux-foundation.org> - 2016-12-08 19:20 +0100
    Re: [RFC, PATCHv1 00/28] 5-level paging hpa@zytor.com - 2016-12-08 19:30 +0100
    Re: [RFC, PATCHv1 00/28] 5-level paging "Kirill A. Shutemov" <kirill@shutemov.name> - 2016-12-08 20:30 +0100
  Re: [RFC, PATCHv1 00/28] 5-level paging Ingo Molnar <mingo@kernel.org> - 2016-12-09 06:10 +0100
    Re: [RFC, PATCHv1 00/28] 5-level paging Arnd Bergmann <arnd@arndb.de> - 2016-12-09 11:30 +0100
      Re: [RFC, PATCHv1 00/28] 5-level paging Catalin Marinas <catalin.marinas@arm.com> - 2016-12-09 12:00 +0100
    Re: [RFC, PATCHv1 00/28] 5-level paging "Kirill A. Shutemov" <kirill@shutemov.name> - 2016-12-09 11:40 +0100
      Re: [RFC, PATCHv1 00/28] 5-level paging Andi Kleen <ak@linux.intel.com> - 2016-12-09 17:50 +0100
        Re: [RFC, PATCHv1 00/28] 5-level paging "Kirill A. Shutemov" <kirill@shutemov.name> - 2016-12-09 18:30 +0100
      Re: [RFC, PATCHv1 00/28] 5-level paging Dave Hansen <dave.hansen@intel.com> - 2016-12-09 17:50 +0100
    Re: [RFC, PATCHv1 00/28] 5-level paging Dave Hansen <dave.hansen@intel.com> - 2016-12-13 22:10 +0100

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