linux-kernel - [PATCH v6 00/23] powerpc/8xx: Use large pages for RAM and IMMR and other improvments

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Date:	Thu,  4 Feb 2016 11:33:00 +0100 (CET)
From:	Christophe Leroy <christophe.leroy@....fr>
To:	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Paul Mackerras <paulus@...ba.org>,
	Michael Ellerman <mpe@...erman.id.au>,
	Scott Wood <oss@...error.net>, Jonathan Corbet <corbet@....net>
Cc:	linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
	linux-doc@...r.kernel.org
Subject: [PATCH v6 00/23] powerpc/8xx: Use large pages for RAM and IMMR and other improvments

The main purpose of this patchset is to dramatically reduce the time
spent in DTLB miss handler. This is achieved by:
1/ Mapping RAM with 8M pages
2/ Mapping IMMR with a fixed 512K page

On a live running system (VoIP gateway for Air Trafic Control), over
a 10 minutes period (with 277s idle), we get 87 millions DTLB misses
and approximatly 35 secondes are spent in DTLB handler.
This represents 5.8% of the overall time and even 10.8% of the
non-idle time.
Among those 87 millions DTLB misses, 15% are on user addresses and
85% are on kernel addresses. And within the kernel addresses, 93%
are on addresses from the linear address space and only 7% are on
addresses from the virtual address space.

Once the full patchset applied, the number of DTLB misses during the
period is reduced to 11.8 millions for a duration of 5.8s, which
represents 2% of the non-idle time.

This patch also includes other miscellaneous improvements:
1/ Handling of CPU6 ERRATA directly in mtspr() C macro to reduce code
specific to PPC8xx
2/ Rewrite of a few non critical ASM functions in C
3/ Removal of some unused items

See related patches for details

Main changes in v3:
* Using fixmap instead of fix address for mapping IMMR

Change in v4:
* Fix of a wrong #if notified by kbuild robot in 07/23

Change in v5:
* Removed use of pmd_val() as L-value
* Adapted to match the new include files layout in Linux 4.5

Change in v6:
* Removed remaining use of pmd_val() as L-value

Christophe Leroy (23):
  powerpc/8xx: Save r3 all the time in DTLB miss handler
  powerpc/8xx: Map linear kernel RAM with 8M pages
  powerpc: Update documentation for noltlbs kernel parameter
  powerpc/8xx: move setup_initial_memory_limit() into 8xx_mmu.c
  powerpc32: Fix pte_offset_kernel() to return NULL for bad pages
  powerpc32: refactor x_mapped_by_bats() and x_mapped_by_tlbcam()
    together
  powerpc/8xx: Fix vaddr for IMMR early remap
  powerpc/8xx: Map IMMR area with 512k page at a fixed address
  powerpc/8xx: CONFIG_PIN_TLB unneeded for CONFIG_PPC_EARLY_DEBUG_CPM
  powerpc/8xx: map more RAM at startup when needed
  powerpc32: Remove useless/wrong MMU:setio progress message
  powerpc32: remove ioremap_base
  powerpc/8xx: Add missing SPRN defines into reg_8xx.h
  powerpc/8xx: Handle CPU6 ERRATA directly in mtspr() macro
  powerpc/8xx: remove special handling of CPU6 errata in set_dec()
  powerpc/8xx: rewrite set_context() in C
  powerpc/8xx: rewrite flush_instruction_cache() in C
  powerpc: add inline functions for cache related instructions
  powerpc32: Remove clear_pages() and define clear_page() inline
  powerpc32: move xxxxx_dcache_range() functions inline
  powerpc: Simplify test in __dma_sync()
  powerpc32: small optimisation in flush_icache_range()
  powerpc32: Remove one insn in mulhdu

 Documentation/kernel-parameters.txt          |   2 +-
 arch/powerpc/Kconfig.debug                   |   1 -
 arch/powerpc/include/asm/cache.h             |  19 +++
 arch/powerpc/include/asm/cacheflush.h        |  52 ++++++-
 arch/powerpc/include/asm/fixmap.h            |  14 ++
 arch/powerpc/include/asm/mmu-8xx.h           |   4 +-
 arch/powerpc/include/asm/nohash/32/pgtable.h |   5 +-
 arch/powerpc/include/asm/page_32.h           |  17 ++-
 arch/powerpc/include/asm/reg.h               |   2 +
 arch/powerpc/include/asm/reg_8xx.h           |  93 ++++++++++++
 arch/powerpc/include/asm/time.h              |   6 +-
 arch/powerpc/kernel/asm-offsets.c            |   8 ++
 arch/powerpc/kernel/head_8xx.S               | 207 +++++++++++++++++----------
 arch/powerpc/kernel/misc_32.S                | 107 ++------------
 arch/powerpc/kernel/ppc_ksyms.c              |   2 +
 arch/powerpc/kernel/ppc_ksyms_32.c           |   1 -
 arch/powerpc/mm/8xx_mmu.c                    | 190 ++++++++++++++++++++++++
 arch/powerpc/mm/Makefile                     |   1 +
 arch/powerpc/mm/dma-noncoherent.c            |   2 +-
 arch/powerpc/mm/fsl_booke_mmu.c              |   4 +-
 arch/powerpc/mm/init_32.c                    |  23 ---
 arch/powerpc/mm/mmu_decl.h                   |  34 +++--
 arch/powerpc/mm/pgtable_32.c                 |  47 +-----
 arch/powerpc/mm/ppc_mmu_32.c                 |   4 +-
 arch/powerpc/platforms/embedded6xx/mpc10x.h  |  10 --
 arch/powerpc/sysdev/cpm_common.c             |  15 +-
 26 files changed, 583 insertions(+), 287 deletions(-)
 create mode 100644 arch/powerpc/mm/8xx_mmu.c

-- 
2.1.0