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authorAnton Blanchard <anton@samba.org>2009-12-06 12:48:33 -0500
committerBenjamin Herrenschmidt <benh@kernel.crashing.org>2009-12-17 22:54:26 -0500
commit030bdc3fd0807b6097a937468859f4b4baf1b950 (patch)
tree0d95e6f6ed8fd9fc1e1b7f0ba29ee9e1ebeaae25 /arch/powerpc/configs/ppc64_defconfig
parent55f2fa147392ffd23cec56cbb3d85ab5b3ebc125 (diff)
powerpc/defconfigs: Set HZ=100 on pseries and ppc64 defconfigs
Now we have high res timers there is less of a reason for a high HZ value. Furthermore I think there a few reasons we should reduce HZ to 100: - Timer interrupt overhead. While this overhead is small, there are applications that are very sensitive to jitter (eg some HPC apps). - Issues with the timer wheel code. When coming out of NO_HZ idle we work our way through the timer code one tick at a time. If we have been idle a long time, this adds up - I sometimes see milliseconds of time spent in that loop. Long term we should fix the timer wheel algorithm, but for now if we reduce HZ then we reduce the amount of work the timer code has to do when coming out of idle. Signed-off-by: Anton Blanchard <anton@samba.org> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Diffstat (limited to 'arch/powerpc/configs/ppc64_defconfig')
-rw-r--r--arch/powerpc/configs/ppc64_defconfig6
1 files changed, 3 insertions, 3 deletions
diff --git a/arch/powerpc/configs/ppc64_defconfig b/arch/powerpc/configs/ppc64_defconfig
index 4b043f973389..7b3804a6e363 100644
--- a/arch/powerpc/configs/ppc64_defconfig
+++ b/arch/powerpc/configs/ppc64_defconfig
@@ -304,11 +304,11 @@ CONFIG_TICK_ONESHOT=y
304CONFIG_NO_HZ=y 304CONFIG_NO_HZ=y
305CONFIG_HIGH_RES_TIMERS=y 305CONFIG_HIGH_RES_TIMERS=y
306CONFIG_GENERIC_CLOCKEVENTS_BUILD=y 306CONFIG_GENERIC_CLOCKEVENTS_BUILD=y
307# CONFIG_HZ_100 is not set 307CONFIG_HZ_100=y
308CONFIG_HZ_250=y 308# CONFIG_HZ_250 is not set
309# CONFIG_HZ_300 is not set 309# CONFIG_HZ_300 is not set
310# CONFIG_HZ_1000 is not set 310# CONFIG_HZ_1000 is not set
311CONFIG_HZ=250 311CONFIG_HZ=100
312CONFIG_SCHED_HRTICK=y 312CONFIG_SCHED_HRTICK=y
313CONFIG_PREEMPT_NONE=y 313CONFIG_PREEMPT_NONE=y
314# CONFIG_PREEMPT_VOLUNTARY is not set 314# CONFIG_PREEMPT_VOLUNTARY is not set