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[PATCH] time_interpolator: Use readq_relaxed() instead of readq().

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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.

It affects sparc64 and ia64 only.  Apparently it makes a significant
difference on ia64.

Signed-off-by: Christoph Lameter <[email protected]>
Cc: john stultz <[email protected]>
Cc: "David S. Miller" <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This commit is contained in:
Christoph Lameter authored and Linus Torvalds committed 2006-03-02 08:33:07 -08:00
1 parent 7f99f06f01
commit 685db65e42
1 file changed
+2 -2
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kernel/timer.c
+2 -2
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@@ -1351,10 +1351,10 @@ static inline u64 time_interpolator_get_cycles(unsigned int src)
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();
}