From: Xiao Wang <xiao.w.wang@intel.com> To: paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu Cc: jerry.shih@sifive.com, nick.knight@sifive.com, ajones@ventanamicro.com, bjorn@rivosinc.com, andy.chiu@sifive.com, viro@zeniv.linux.org.uk, cleger@rivosinc.com, alexghiti@rivosinc.com, haicheng.li@intel.com, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, Xiao Wang <xiao.w.wang@intel.com> Subject: [PATCH] riscv: uaccess: Relax the threshold for fast path Date: Wed, 13 Mar 2024 17:19:29 +0800 [thread overview] Message-ID: <20240313091929.4029960-1-xiao.w.wang@intel.com> (raw) The bytes copy for unaligned head would cover at most SZREG-1 bytes, so it's better to set the threshold as >= (SZREG-1 + word_copy stride size) which equals to 9*SZREG-1. Signed-off-by: Xiao Wang <xiao.w.wang@intel.com> --- arch/riscv/lib/uaccess.S | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/riscv/lib/uaccess.S b/arch/riscv/lib/uaccess.S index bc22c078aba8..2e665f8f8fcc 100644 --- a/arch/riscv/lib/uaccess.S +++ b/arch/riscv/lib/uaccess.S @@ -44,7 +44,7 @@ SYM_FUNC_START(fallback_scalar_usercopy) * Use byte copy only if too small. * SZREG holds 4 for RV32 and 8 for RV64 */ - li a3, 9*SZREG /* size must be larger than size in word_copy */ + li a3, 9*SZREG-1 /* size must >= (word_copy stride + SZREG-1) */ bltu a2, a3, .Lbyte_copy_tail /* -- 2.25.1
WARNING: multiple messages have this Message-ID (diff)
From: Xiao Wang <xiao.w.wang@intel.com> To: paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu Cc: jerry.shih@sifive.com, nick.knight@sifive.com, ajones@ventanamicro.com, bjorn@rivosinc.com, andy.chiu@sifive.com, viro@zeniv.linux.org.uk, cleger@rivosinc.com, alexghiti@rivosinc.com, haicheng.li@intel.com, linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, Xiao Wang <xiao.w.wang@intel.com> Subject: [PATCH] riscv: uaccess: Relax the threshold for fast path Date: Wed, 13 Mar 2024 17:19:29 +0800 [thread overview] Message-ID: <20240313091929.4029960-1-xiao.w.wang@intel.com> (raw) The bytes copy for unaligned head would cover at most SZREG-1 bytes, so it's better to set the threshold as >= (SZREG-1 + word_copy stride size) which equals to 9*SZREG-1. Signed-off-by: Xiao Wang <xiao.w.wang@intel.com> --- arch/riscv/lib/uaccess.S | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/riscv/lib/uaccess.S b/arch/riscv/lib/uaccess.S index bc22c078aba8..2e665f8f8fcc 100644 --- a/arch/riscv/lib/uaccess.S +++ b/arch/riscv/lib/uaccess.S @@ -44,7 +44,7 @@ SYM_FUNC_START(fallback_scalar_usercopy) * Use byte copy only if too small. * SZREG holds 4 for RV32 and 8 for RV64 */ - li a3, 9*SZREG /* size must be larger than size in word_copy */ + li a3, 9*SZREG-1 /* size must >= (word_copy stride + SZREG-1) */ bltu a2, a3, .Lbyte_copy_tail /* -- 2.25.1 _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv
next reply other threads:[~2024-03-13 9:33 UTC|newest] Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top 2024-03-13 9:19 Xiao Wang [this message] 2024-03-13 9:19 ` [PATCH] riscv: uaccess: Relax the threshold for fast path Xiao Wang 2024-05-03 12:14 ` Alexandre Ghiti 2024-05-03 12:14 ` Alexandre Ghiti
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