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Subject: [PATCH v4 4/5] arm64: mremap speedup - Enable HAVE_MOVE_PUD
From:   Kalesh Singh <kaleshsingh@google.com>
Cc:     surenb@google.com, minchan@google.com, joelaf@google.com,
        lokeshgidra@google.com, kaleshsingh@google.com,
        kernel-team@android.com,
        "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
        Shuah Khan <shuah@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>,
        Kees Cook <keescook@chromium.org>,
        Josh Poimboeuf <jpoimboe@redhat.com>,
        Sami Tolvanen <samitolvanen@google.com>,
        Masahiro Yamada <masahiroy@kernel.org>,
        Arnd Bergmann <arnd@arndb.de>,
        Frederic Weisbecker <frederic@kernel.org>,
        Krzysztof Kozlowski <krzk@kernel.org>,
        Hassan Naveed <hnaveed@wavecomp.com>,
        Christian Brauner <christian.brauner@ubuntu.com>,
        Stephen Boyd <sboyd@kernel.org>,
        Anshuman Khandual <anshuman.khandual@arm.com>,
        Gavin Shan <gshan@redhat.com>, Mike Rapoport <rppt@kernel.org>,
        Steven Price <steven.price@arm.com>,
        Jia He <justin.he@arm.com>, John Hubbard <jhubbard@nvidia.com>,
        Ram Pai <linuxram@us.ibm.com>,
        Ralph Campbell <rcampbell@nvidia.com>,
        Mina Almasry <almasrymina@google.com>,
        Sandipan Das <sandipan@linux.ibm.com>,
        Dave Hansen <dave.hansen@intel.com>,
        Brian Geffon <bgeffon@google.com>,
        Masami Hiramatsu <mhiramat@kernel.org>,
        Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>,
        SeongJae Park <sjpark@amazon.de>, linux-kernel@vger.kernel.org,
        linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org,
        linux-kselftest@vger.kernel.org
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HAVE_MOVE_PUD enables remapping pages at the PUD level if both the
source and destination addresses are PUD-aligned.

With HAVE_MOVE_PUD enabled it can be inferred that there is approximately
a 19x improvement in performance on arm64. (See data below).

------- Test Results ---------

The following results were obtained using a 5.4 kernel, by remapping
a PUD-aligned, 1GB sized region to a PUD-aligned destination.
The results from 10 iterations of the test are given below:

Total mremap times for 1GB data on arm64. All times are in nanoseconds.

Control          HAVE_MOVE_PUD

1247761          74271
1219896          46771
1094792          59687
1227760          48385
1043698          76666
1101771          50365
1159896          52500
1143594          75261
1025833          61354
1078125          48697

1134312.6        59395.7    <-- Mean time in nanoseconds

A 1GB mremap completion time drops from ~1.1 milliseconds
to ~59 microseconds on arm64. (~19x speed up).

Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
---
Changes in v3:
  - Add set_pud_at() macro - Used by move_normal_pud().

Changes in v4:
  - Add Kirill's Acked-by.

 arch/arm64/Kconfig               | 1 +
 arch/arm64/include/asm/pgtable.h | 1 +
 2 files changed, 2 insertions(+)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 434d6791e869..7191a79fb44d 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -124,6 +124,7 @@ config ARM64
 	select HANDLE_DOMAIN_IRQ
 	select HARDIRQS_SW_RESEND
 	select HAVE_MOVE_PMD
+	select HAVE_MOVE_PUD
 	select HAVE_PCI
 	select HAVE_ACPI_APEI if (ACPI && EFI)
 	select HAVE_ALIGNED_STRUCT_PAGE if SLUB
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index a11bf52e0c38..0b0b36974757 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -454,6 +454,7 @@ static inline pmd_t pmd_mkdevmap(pmd_t pmd)
 #define pfn_pud(pfn,prot)	__pud(__phys_to_pud_val((phys_addr_t)(pfn) << PAGE_SHIFT) | pgprot_val(prot))
 
 #define set_pmd_at(mm, addr, pmdp, pmd)	set_pte_at(mm, addr, (pte_t *)pmdp, pmd_pte(pmd))
+#define set_pud_at(mm, addr, pudp, pud)	set_pte_at(mm, addr, (pte_t *)pudp, pud_pte(pud))
 
 #define __p4d_to_phys(p4d)	__pte_to_phys(p4d_pte(p4d))
 #define __phys_to_p4d_val(phys)	__phys_to_pte_val(phys)
-- 
2.28.0.1011.ga647a8990f-goog