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Subject[PATCH] Prevent users from disabling tickless

Disabling NO_HZ has a serious negative effect on performance -- an extra
70us per I/O. Prevent users from deselecting it.

Signed-off-by: Matthew Wilcox <willy@linux.intel.com>

diff --git a/kernel/time/Kconfig b/kernel/time/Kconfig
index f06a8a3..55b9a04 100644
--- a/kernel/time/Kconfig
+++ b/kernel/time/Kconfig
@@ -5,13 +5,9 @@ config TICK_ONESHOT
bool

config NO_HZ
- bool "Tickless System (Dynamic Ticks)"
+ def_bool y
depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS
select TICK_ONESHOT
- help
- This option enables a tickless system: timer interrupts will
- only trigger on an as-needed basis both when the system is
- busy and when the system is idle.

config HIGH_RES_TIMERS
bool "High Resolution Timer Support"
--
Matthew Wilcox Intel Open Source Technology Centre
"Bill, look, we understand that you're interested in selling us this
operating system, but compare it to ours. We can't possibly take such
a retrograde step."


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