From: Samuel Holland <samuel.holland@sifive.com>
To: Palmer Dabbelt <palmer@dabbelt.com>, linux-riscv@lists.infradead.org
Cc: Mark Rutland <mark.rutland@arm.com>,
David Laight <David.Laight@ACULAB.COM>,
Arnd Bergmann <arnd@arndb.de>,
Alexandre Ghiti <alexghiti@rivosinc.com>,
Samuel Holland <samuel.holland@sifive.com>
Subject: [PATCH v2 0/2] riscv: access_ok() optimization
Date: Wed, 27 Mar 2024 07:38:11 -0700 [thread overview]
Message-ID: <20240327143858.711792-1-samuel.holland@sifive.com> (raw)
This series optimizes access_ok() by defining TASK_SIZE_MAX. At Alex's
suggestion, I also tried making TASK_SIZE constant (specifically by
making PGDIR_SHIFT a variable instead of a ternary expression, then
replacing the load with an immediate using ALTERNATIVE). This appeared
to slightly improve performance on some implementations (C906) but
regressed it on others (FU740). So I am leaving further optimizations to
a later series.
Changes in v2:
- Add a patch removing PGDIR_SIZE_L3 and TASK_SIZE_MIN
- Set TASK_SIZE_MAX to LONG_MAX to optimize the comparison
- Reword the commit message
Samuel Holland (2):
riscv: Remove PGDIR_SIZE_L3 and TASK_SIZE_MIN
riscv: Define TASK_SIZE_MAX for __access_ok()
arch/riscv/include/asm/pgtable-64.h | 2 --
arch/riscv/include/asm/pgtable.h | 3 +--
2 files changed, 1 insertion(+), 4 deletions(-)
--
2.43.1
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next reply other threads:[~2024-03-27 14:39 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-27 14:38 Samuel Holland [this message]
2024-03-27 14:38 ` [PATCH v2 1/2] riscv: Remove PGDIR_SIZE_L3 and TASK_SIZE_MIN Samuel Holland
2024-03-27 16:24 ` Arnd Bergmann
2024-04-04 7:33 ` Alexandre Ghiti
2024-03-27 14:38 ` [PATCH v2 2/2] riscv: Define TASK_SIZE_MAX for __access_ok() Samuel Holland
2024-03-27 16:24 ` Arnd Bergmann
2024-04-04 7:38 ` Alexandre Ghiti
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