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-rw-r--r--arch/arm/Kconfig16
1 files changed, 16 insertions, 0 deletions
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index c857111ab96..3473f8b8ede 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1091,6 +1091,22 @@ config ALIGNMENT_TRAP
correct operation of some network protocols. With an IP-only
configuration it is safe to say N, otherwise say Y.
+config UACCESS_WITH_MEMCPY
+ bool "Use kernel mem{cpy,set}() for {copy_to,clear}_user() (EXPERIMENTAL)"
+ depends on MMU && EXPERIMENTAL
+ default y if CPU_FEROCEON
+ help
+ Implement faster copy_to_user and clear_user methods for CPU
+ cores where a 8-word STM instruction give significantly higher
+ memory write throughput than a sequence of individual 32bit stores.
+
+ A possible side effect is a slight increase in scheduling latency
+ between threads sharing the same address space if they invoke
+ such copy operations with large buffers.
+
+ However, if the CPU data cache is using a write-allocate mode,
+ this option is unlikely to provide any performance gain.
+
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