linux-kernel - [PATCH v2 0/6] Speed up mremap on large regions

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Message-Id: <20201002162101.665549-1-kaleshsingh@google.com>
Date:   Fri,  2 Oct 2020 16:20:45 +0000
From:   Kalesh Singh <kaleshsingh@...gle.com>
To:     unlisted-recipients:; (no To-header on input)
Cc:     surenb@...gle.com, minchan@...gle.com, joelaf@...gle.com,
        lokeshgidra@...gle.com, kaleshsingh@...gle.com,
        kernel-team@...roid.com, Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Shuah Khan <shuah@...nel.org>,
        Kees Cook <keescook@...omium.org>,
        "Aneesh Kumar K.V" <aneesh.kumar@...ux.ibm.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Arnd Bergmann <arnd@...db.de>,
        Masahiro Yamada <masahiroy@...nel.org>,
        Sami Tolvanen <samitolvanen@...gle.com>,
        Frederic Weisbecker <frederic@...nel.org>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Hassan Naveed <hnaveed@...ecomp.com>,
        Christian Brauner <christian.brauner@...ntu.com>,
        Mark Rutland <mark.rutland@....com>,
        Mark Brown <broonie@...nel.org>,
        Mike Rapoport <rppt@...nel.org>, Gavin Shan <gshan@...hat.com>,
        Zhenyu Ye <yezhenyu2@...wei.com>,
        Steven Price <steven.price@....com>,
        Jia He <justin.he@....com>, John Hubbard <jhubbard@...dia.com>,
        William Kucharski <william.kucharski@...cle.com>,
        Mike Kravetz <mike.kravetz@...cle.com>,
        Ralph Campbell <rcampbell@...dia.com>,
        Mina Almasry <almasrymina@...gle.com>,
        Ram Pai <linuxram@...ibm.com>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Sandipan Das <sandipan@...ux.ibm.com>,
        Dave Hansen <dave.hansen@...el.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Brian Geffon <bgeffon@...gle.com>,
        Kamalesh Babulal <kamalesh@...ux.vnet.ibm.com>,
        SeongJae Park <sjpark@...zon.de>, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-mm@...ck.org,
        linux-kselftest@...r.kernel.org
Subject: [PATCH v2 0/6] Speed up mremap on large regions

This version 2 of the mremap speed up patches previously posted at:
https://lore.kernel.org/r/20200930222130.4175584-1-kaleshsingh@google.com

mremap time can be optimized by moving entries at the PMD/PUD level if
the source and destination addresses are PMD/PUD-aligned and
PMD/PUD-sized. Enable moving at the PMD and PUD levels on arm64 and
x86. Other architectures where this type of move is supported and known to
be safe can also opt-in to these optimizations by enabling HAVE_MOVE_PMD
and HAVE_MOVE_PUD.

Observed Performance Improvements for remapping a PUD-aligned 1GB-sized
region on x86 and arm64:

    - HAVE_MOVE_PMD is already enabled on x86 : N/A
    - Enabling HAVE_MOVE_PUD on x86   : ~13x speed up

    - Enabling HAVE_MOVE_PMD on arm64 : ~ 8x speed up
    - Enabling HAVE_MOVE_PUD on arm64 : ~19x speed up

          Altogether, HAVE_MOVE_PMD and HAVE_MOVE_PUD
          give a total of ~150x speed up on arm64.

Changes in v2:
  - Reduce mremap_test time by only validating a configurable
    threshold of the remapped region, as per John.
  - Use a random pattern for mremap validation. Provide pattern
    seed in test output, as per John.
  - Moved set_pud_at() to separate patch, per Kirill.
  - Use switch() instead of ifs in move_pgt_entry(), per Kirill.
  - Update commit message with description of Android
    garbage collector use case for HAVE_MOVE_PUD, as per Joel.
  - Fix build test error reported by kernel test robot in [1].

[1] https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org/thread/CKPGL4FH4NG7TGH2CVYX2UX76L25BTA3/

Kalesh Singh (6):
  kselftests: vm: Add mremap tests
  arm64: mremap speedup - Enable HAVE_MOVE_PMD
  mm: Speedup mremap on 1GB or larger regions
  arm64: Add set_pud_at() functions
  arm64: mremap speedup - Enable HAVE_MOVE_PUD
  x86: mremap speedup - Enable HAVE_MOVE_PUD

 arch/Kconfig                             |   7 +
 arch/arm64/Kconfig                       |   2 +
 arch/arm64/include/asm/pgtable.h         |   1 +
 arch/x86/Kconfig                         |   1 +
 mm/mremap.c                              | 220 +++++++++++++--
 tools/testing/selftests/vm/.gitignore    |   1 +
 tools/testing/selftests/vm/Makefile      |   1 +
 tools/testing/selftests/vm/mremap_test.c | 333 +++++++++++++++++++++++
 tools/testing/selftests/vm/run_vmtests   |  11 +
 9 files changed, 547 insertions(+), 30 deletions(-)
 create mode 100644 tools/testing/selftests/vm/mremap_test.c


base-commit: 472e5b056f000a778abb41f1e443de58eb259783
-- 
2.28.0.806.g8561365e88-goog