From fddd87d6e135924b92499917bace103e46c22d00 Mon Sep 17 00:00:00 2001 From: Richard Henderson Date: Fri, 12 Jul 2013 16:15:56 -0700 Subject: alpha: Allow HZ to be configured With the 1024Hz default, we spend 50% of QEMU emulation processing timer interrupts. Signed-off-by: Richard Henderson --- arch/alpha/Kconfig | 36 ++++++++++++++++++++++++++++++++++-- 1 file changed, 34 insertions(+), 2 deletions(-) (limited to 'arch/alpha/Kconfig') diff --git a/arch/alpha/Kconfig b/arch/alpha/Kconfig index 51cc8c353164..a67b971c830a 100644 --- a/arch/alpha/Kconfig +++ b/arch/alpha/Kconfig @@ -627,9 +627,41 @@ config VERBOSE_MCHECK_ON Take the default (1) unless you want more control or more info. +choice + prompt "Timer interrupt frequency (HZ)?" + default HZ_128 if ALPHA_QEMU + default HZ_1200 if ALPHA_RAWHIDE + default HZ_1024 + ---help--- + The frequency at which timer interrupts occur. A high frequency + minimizes latency, whereas a low frequency minimizes overhead of + process accounting. The later effect is especially significant + when being run under QEMU. + + Note that some Alpha hardware cannot change the interrupt frequency + of the timer. If unsure, say 1024 (or 1200 for Rawhide). + + config HZ_32 + bool "32 Hz" + config HZ_64 + bool "64 Hz" + config HZ_128 + bool "128 Hz" + config HZ_256 + bool "256 Hz" + config HZ_1024 + bool "1024 Hz" + config HZ_1200 + bool "1200 Hz" +endchoice + config HZ - int - default 1200 if ALPHA_RAWHIDE + int + default 32 if HZ_32 + default 64 if HZ_64 + default 128 if HZ_128 + default 256 if HZ_256 + default 1200 if HZ_1200 default 1024 source "drivers/pci/Kconfig" -- cgit v1.2.3-59-g8ed1b