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 <catalin.marinas@arm.com> Reviewed-by: Trilok Soni <tsoni@codeaurora.org> Signed-off-by: Joonwoo Park <joonwoop@codeaurora.org> Signed-off-by: Will Deacon <will.deacon@arm.com>
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@ -25,12 +25,26 @@
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*/
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void __memcpy_fromio(void *to, const volatile void __iomem *from, size_t count)
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{
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unsigned char *t = to;
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while (count) {
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count--;
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*t = readb(from);
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t++;
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while (count && (!IS_ALIGNED((unsigned long)from, 8) ||
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!IS_ALIGNED((unsigned long)to, 8))) {
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*(u8 *)to = __raw_readb(from);
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from++;
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to++;
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count--;
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}
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while (count >= 8) {
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*(u64 *)to = __raw_readq(from);
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from += 8;
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to += 8;
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count -= 8;
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}
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while (count) {
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*(u8 *)to = __raw_readb(from);
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from++;
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to++;
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count--;
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}
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}
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EXPORT_SYMBOL(__memcpy_fromio);
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@ -40,12 +54,26 @@ EXPORT_SYMBOL(__memcpy_fromio);
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*/
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void __memcpy_toio(volatile void __iomem *to, const void *from, size_t count)
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{
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const unsigned char *f = from;
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while (count) {
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count--;
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writeb(*f, to);
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f++;
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while (count && (!IS_ALIGNED((unsigned long)to, 8) ||
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!IS_ALIGNED((unsigned long)from, 8))) {
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__raw_writeb(*(volatile u8 *)from, to);
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from++;
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to++;
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count--;
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}
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while (count >= 8) {
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__raw_writeq(*(volatile u64 *)from, to);
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from += 8;
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to += 8;
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count -= 8;
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}
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while (count) {
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__raw_writeb(*(volatile u8 *)from, to);
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from++;
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to++;
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count--;
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}
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}
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EXPORT_SYMBOL(__memcpy_toio);
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@ -55,10 +83,28 @@ EXPORT_SYMBOL(__memcpy_toio);
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*/
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void __memset_io(volatile void __iomem *dst, int c, size_t count)
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{
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while (count) {
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count--;
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writeb(c, dst);
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u64 qc = (u8)c;
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qc |= qc << 8;
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qc |= qc << 16;
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qc |= qc << 32;
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while (count && !IS_ALIGNED((unsigned long)dst, 8)) {
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__raw_writeb(c, dst);
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dst++;
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count--;
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}
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while (count >= 8) {
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__raw_writeq(qc, dst);
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dst += 8;
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count -= 8;
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}
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while (count) {
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__raw_writeb(c, dst);
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dst++;
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count--;
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}
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}
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EXPORT_SYMBOL(__memset_io);
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