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arm64: optimize memcpy_{from,to}io() and memset_io()

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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>
This commit is contained in:
Joonwoo Park 2014-10-21 01:59:03 +01:00 committed by Will Deacon
parent 4ee2098081
commit 70ddb63a88
1 changed files with 59 additions and 13 deletions
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72
arch/arm64/kernel/io.c
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@ -25,12 +25,26 @@
*/
void __memcpy_fromio(void *to, const volatile void __iomem *from, size_t count)
{
unsigned char *t = to;
while (count) {
count--;
*t = readb(from);
t++;
while (count && (!IS_ALIGNED((unsigned long)from, 8) ||
!IS_ALIGNED((unsigned long)to, 8))) {
*(u8 *)to = __raw_readb(from);
from++;
to++;
count--;
}
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) {
count--;
writeb(*f, to);
f++;
while (count && (!IS_ALIGNED((unsigned long)to, 8) ||
!IS_ALIGNED((unsigned long)from, 8))) {
__raw_writeb(*(volatile u8 *)from, to);
from++;
to++;
count--;
}
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) {
count--;
writeb(c, dst);
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--;
}
while (count >= 8) {
__raw_writeq(qc, dst);
dst += 8;
count -= 8;
}
while (count) {
__raw_writeb(c, dst);
dst++;
count--;
}
}
EXPORT_SYMBOL(__memset_io);