Merge branch 'copy_user' of git://git.marvell.com/orion into devel

[sfrench/cifs-2.6.git] / arch / arm / Kconfig

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index c857111ab9642e468b59afa83c963c91422e6d65..3473f8b8ede689a53a565a34eefb6178d1fa3157 100644 (file)
--- 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.
+
 endmenu
 
 menu "Boot options"