From: Charlie Jenkins <charlie@rivosinc.com> To: Alexandre Ghiti <alexghiti@rivosinc.com>, Paul Walmsley <paul.walmsley@sifive.com>, Palmer Dabbelt <palmer@dabbelt.com>, Albert Ou <aou@eecs.berkeley.edu>, Shuah Khan <shuah@kernel.org>, Jonathan Corbet <corbet@lwn.net>, Yangyu Chen <cyy@cyyself.name> Cc: linux-mm@kvack.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-doc@vger.kernel.org, Charlie Jenkins <charlie@rivosinc.com> Subject: [PATCH v2 0/3] riscv: mm: Use hint address in mmap if available Date: Tue, 30 Jan 2024 11:04:29 -0800 [thread overview] Message-ID: <20240130-use_mmap_hint_address-v2-0-f34ebfd33053@rivosinc.com> (raw) On riscv, mmap currently returns an address from the largest address space that can fit entirely inside of the hint address. This makes it such that the hint address is almost never returned. This patch raises the mappable area up to and including the hint address. This allows mmap to often return the hint address, which allows a performance improvement over searching for a valid address as well as making the behavior more similar to other architectures. Note that a previous patch introduced stronger semantics compared to other architectures for riscv mmap. On riscv, mmap will not use bits in the upper bits of the virtual address depending on the hint address. On other architectures, a random address is returned in the address space requested. On all architectures the hint address will be returned if it is available. This allows riscv applications to configure how many bits in the virtual address should be left empty. This has the two benefits of being able to request address spaces that are smaller than the default and doesn't require the application to know the page table layout of riscv. Signed-off-by: Charlie Jenkins <charlie@rivosinc.com> --- Changes in v2: - Add back forgotten "mmap_end = STACK_TOP_MAX" - Link to v1: https://lore.kernel.org/r/20240129-use_mmap_hint_address-v1-0-4c74da813ba1@rivosinc.com --- Charlie Jenkins (3): riscv: mm: Use hint address in mmap if available selftests: riscv: Generalize mm selftests docs: riscv: Define behavior of mmap Documentation/arch/riscv/vm-layout.rst | 16 ++-- arch/riscv/include/asm/processor.h | 22 +++--- tools/testing/selftests/riscv/mm/mmap_bottomup.c | 20 +---- tools/testing/selftests/riscv/mm/mmap_default.c | 20 +---- tools/testing/selftests/riscv/mm/mmap_test.h | 93 +++++++++++++----------- 5 files changed, 67 insertions(+), 104 deletions(-) --- base-commit: 556e2d17cae620d549c5474b1ece053430cd50bc change-id: 20240119-use_mmap_hint_address-f9f4b1b6f5f1 -- - Charlie _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv
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From: Charlie Jenkins <charlie@rivosinc.com> To: Alexandre Ghiti <alexghiti@rivosinc.com>, Paul Walmsley <paul.walmsley@sifive.com>, Palmer Dabbelt <palmer@dabbelt.com>, Albert Ou <aou@eecs.berkeley.edu>, Shuah Khan <shuah@kernel.org>, Jonathan Corbet <corbet@lwn.net>, Yangyu Chen <cyy@cyyself.name> Cc: linux-mm@kvack.org, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-doc@vger.kernel.org, Charlie Jenkins <charlie@rivosinc.com> Subject: [PATCH v2 0/3] riscv: mm: Use hint address in mmap if available Date: Tue, 30 Jan 2024 11:04:29 -0800 [thread overview] Message-ID: <20240130-use_mmap_hint_address-v2-0-f34ebfd33053@rivosinc.com> (raw) On riscv, mmap currently returns an address from the largest address space that can fit entirely inside of the hint address. This makes it such that the hint address is almost never returned. This patch raises the mappable area up to and including the hint address. This allows mmap to often return the hint address, which allows a performance improvement over searching for a valid address as well as making the behavior more similar to other architectures. Note that a previous patch introduced stronger semantics compared to other architectures for riscv mmap. On riscv, mmap will not use bits in the upper bits of the virtual address depending on the hint address. On other architectures, a random address is returned in the address space requested. On all architectures the hint address will be returned if it is available. This allows riscv applications to configure how many bits in the virtual address should be left empty. This has the two benefits of being able to request address spaces that are smaller than the default and doesn't require the application to know the page table layout of riscv. Signed-off-by: Charlie Jenkins <charlie@rivosinc.com> --- Changes in v2: - Add back forgotten "mmap_end = STACK_TOP_MAX" - Link to v1: https://lore.kernel.org/r/20240129-use_mmap_hint_address-v1-0-4c74da813ba1@rivosinc.com --- Charlie Jenkins (3): riscv: mm: Use hint address in mmap if available selftests: riscv: Generalize mm selftests docs: riscv: Define behavior of mmap Documentation/arch/riscv/vm-layout.rst | 16 ++-- arch/riscv/include/asm/processor.h | 22 +++--- tools/testing/selftests/riscv/mm/mmap_bottomup.c | 20 +---- tools/testing/selftests/riscv/mm/mmap_default.c | 20 +---- tools/testing/selftests/riscv/mm/mmap_test.h | 93 +++++++++++++----------- 5 files changed, 67 insertions(+), 104 deletions(-) --- base-commit: 556e2d17cae620d549c5474b1ece053430cd50bc change-id: 20240119-use_mmap_hint_address-f9f4b1b6f5f1 -- - Charlie
next reply other threads:[~2024-01-30 19:04 UTC|newest] Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top 2024-01-30 19:04 Charlie Jenkins [this message] 2024-01-30 19:04 ` [PATCH v2 0/3] riscv: mm: Use hint address in mmap if available Charlie Jenkins 2024-01-30 19:04 ` [PATCH v2 1/3] " Charlie Jenkins 2024-01-30 19:04 ` Charlie Jenkins 2024-01-30 19:15 ` Yangyu Chen 2024-01-30 19:15 ` Yangyu Chen 2024-01-30 21:51 ` Charlie Jenkins 2024-01-30 21:51 ` Charlie Jenkins 2024-01-30 19:04 ` [PATCH v2 2/3] selftests: riscv: Generalize mm selftests Charlie Jenkins 2024-01-30 19:04 ` Charlie Jenkins 2024-01-30 19:04 ` [PATCH v2 3/3] docs: riscv: Define behavior of mmap Charlie Jenkins 2024-01-30 19:04 ` Charlie Jenkins 2024-03-20 20:50 ` [PATCH v2 0/3] riscv: mm: Use hint address in mmap if available patchwork-bot+linux-riscv 2024-03-20 20:50 ` patchwork-bot+linux-riscv
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