From 70ddb63a88bfd45eb6abe36e2bf4f8f351a447d7 Mon Sep 17 00:00:00 2001 From: Joonwoo Park Date: Tue, 21 Oct 2014 01:59:03 +0100 Subject: [PATCH] arm64: optimize memcpy_{from,to}io() and memset_io() Optimize memcpy_{from,to}io() and memset_io() by transferring in 64 bit as much as possible with minimized barrier usage. This simplest optimization brings faster throughput compare to current byte-by-byte read and write with barrier in the loop. Code's skeleton is taken from the powerpc. Link: http://lkml.kernel.org/p/20141020133304.GH23751@e104818-lin.cambridge.arm.com Reviewed-by: Catalin Marinas Reviewed-by: Trilok Soni Signed-off-by: Joonwoo Park Signed-off-by: Will Deacon --- arch/arm64/kernel/io.c | 66 +++++++++++++++++++++++++++++++++++------- 1 file changed, 56 insertions(+), 10 deletions(-) diff --git a/arch/arm64/kernel/io.c b/arch/arm64/kernel/io.c index 7d37ead4d199..354be2a872ae 100644 --- a/arch/arm64/kernel/io.c +++ b/arch/arm64/kernel/io.c @@ -25,12 +25,26 @@ */ void __memcpy_fromio(void *to, const volatile void __iomem *from, size_t count) { - unsigned char *t = to; - while (count) { + while (count && (!IS_ALIGNED((unsigned long)from, 8) || + !IS_ALIGNED((unsigned long)to, 8))) { + *(u8 *)to = __raw_readb(from); + from++; + to++; count--; - *t = readb(from); - t++; + } + + while (count >= 8) { + *(u64 *)to = __raw_readq(from); + from += 8; + to += 8; + count -= 8; + } + + while (count) { + *(u8 *)to = __raw_readb(from); from++; + to++; + count--; } } EXPORT_SYMBOL(__memcpy_fromio); @@ -40,12 +54,26 @@ EXPORT_SYMBOL(__memcpy_fromio); */ void __memcpy_toio(volatile void __iomem *to, const void *from, size_t count) { - const unsigned char *f = from; - while (count) { + while (count && (!IS_ALIGNED((unsigned long)to, 8) || + !IS_ALIGNED((unsigned long)from, 8))) { + __raw_writeb(*(volatile u8 *)from, to); + from++; + to++; count--; - writeb(*f, to); - f++; + } + + while (count >= 8) { + __raw_writeq(*(volatile u64 *)from, to); + from += 8; + to += 8; + count -= 8; + } + + while (count) { + __raw_writeb(*(volatile u8 *)from, to); + from++; to++; + count--; } } EXPORT_SYMBOL(__memcpy_toio); @@ -55,10 +83,28 @@ EXPORT_SYMBOL(__memcpy_toio); */ void __memset_io(volatile void __iomem *dst, int c, size_t count) { - while (count) { + u64 qc = (u8)c; + + qc |= qc << 8; + qc |= qc << 16; + qc |= qc << 32; + + while (count && !IS_ALIGNED((unsigned long)dst, 8)) { + __raw_writeb(c, dst); + dst++; count--; - writeb(c, dst); + } + + while (count >= 8) { + __raw_writeq(qc, dst); + dst += 8; + count -= 8; + } + + while (count) { + __raw_writeb(c, dst); dst++; + count--; } } EXPORT_SYMBOL(__memset_io); -- 2.20.1