On some platforms readq performs additional work to make sure I/O is done in
a coherent way. This is not needed for time retrieval as done by the time interpolator.
So we can use readq_relaxed instead which will improve performance.
Signed-off-by: Christoph Lameter <[email protected]>
Index: linux-2.6.16-rc4/kernel/timer.c
===================================================================
--- linux-2.6.16-rc4.orig/kernel/timer.c 2006-02-17 14:23:45.000000000 -0800
+++ linux-2.6.16-rc4/kernel/timer.c 2006-02-23 14:03:02.000000000 -0800
@@ -1351,10 +1351,10 @@ static inline u64 time_interpolator_get_
return x();
case TIME_SOURCE_MMIO64 :
- return readq((void __iomem *) time_interpolator->addr);
+ return readq_relaxed((void __iomem *) time_interpolator->addr);
case TIME_SOURCE_MMIO32 :
- return readl((void __iomem *) time_interpolator->addr);
+ return readl_relaxed((void __iomem *) time_interpolator->addr);
default: return get_cycles();
}