TWD: enable one-shot mode
Subsystems (3)
PATCH 1/1 TWD: enable one-shot mode
Allow one shot timer mode to be used with the TWD. This allows NOHZ mode to be used on SMP systems using the TWD localtimer.
Tested on Versatile Express.
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Acks/Tested-by's would be appreciated, thanks.
Merry Christmas.
arch/arm/Kconfig | 1 + 1 file changed, 1 insertion(+)
arch/arm/Kconfig +1 -0
@@ -1282,6 +1282,7 @@ config HAVE_ARM_SCU config HAVE_ARM_TWD bool depends on SMP + select TICK_ONESHOT help This options enables support for the ARM timer and watchdog unit
PATCH 1/1 TWD: enable one-shot mode
2010/12/24 Russell King - ARM Linux <[email protected]>:
Quoted 8 lines
Allow one shot timer mode to be used with the TWD. ?This allows NOHZ mode to be used on SMP systems using the TWD localtimer.
Tested on Versatile Express.
Signed-off-by Russell King <[email protected]>---
Acks/Tested-by's would be appreciated, thanks.
Tested on the U8500 and doesn't seem to break anything...
Local interrupts after a few minutes of use before patching (and enabling NO_HZ):
LOC: 8203 8224
After patching;
LOC: 233 322
Looks like it's working, too.
Yours,
Linus Walleij
PATCH 1/1 TWD: enable one-shot mode
In reply to Russell King - ARM LinuxQuoted 9 lines · Russell King - ARM Linux
Allow one shot timer mode to be used with the TWD. This allows NOHZ mode to be used on SMP systems using the TWD localtimer.
Tested on Versatile Express.
Signed-off-by Russell King <[email protected]>---
Acks/Tested-by's would be appreciated, thanks.
I see this patch was already tested and merged but can you elaborate on why this was done? From what I understand, NOHZ selects one-shot (like is done in this patch), so why don't the machines with a TWD choose NOHZ or high res timers?
Putting it another way, if my machine supports a oneshot capable clockevent device should I be selecting oneshot regardless of the NOHZ and high res config option being chosen?
Signature · 2 lines
Sent by an employee of the Qualcomm Innovation Center, Inc. The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.
PATCH 1/1 TWD: enable one-shot mode
Quoted 11 lines · Stephen Boyd
Quoted 9 lines · Russell King - ARM Linux
Allow one shot timer mode to be used with the TWD. This allows NOHZ mode to be used on SMP systems using the TWD localtimer.
Tested on Versatile Express.
Signed-off-by Russell King <[email protected]>---
Acks/Tested-by's would be appreciated, thanks.
Quoted 4 lines
I see this patch was already tested and merged but can you elaborate on why this was done? From what I understand, NOHZ selects one-shot (like is done in this patch), so why don't the machines with a TWD choose NOHZ or high res timers?
You're right - so it's not actually required. It should probably be reverted, though it does no damage...
PATCH 1/1 TWD: enable one-shot mode
Quoted 9 lines · Russell King - ARM Linux
Quoted 5 lines · Stephen Boyd
I see this patch was already tested and merged but can you elaborate on why this was done? From what I understand, NOHZ selects one-shot (like is done in this patch), so why don't the machines with a TWD choose NOHZ or high res timers?
You're right - so it's not actually required. It should probably be reverted, though it does no damage...
Now I'm wondering why there are other 'select TICK_ONESHOT' lines in arch/arm/Kconfig. Can we just remove them all? Otherwise it feels like we're making it confusing for others later on.
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arch/arm/Kconfig +0 -4
@@ -532,7 +532,6 @@ config ARCH_MMP select CLKDEV_LOOKUP select GENERIC_CLOCKEVENTS select HAVE_SCHED_CLOCK - select TICK_ONESHOT select PLAT_PXA select SPARSE_IRQ help
@@ -613,7 +612,6 @@ config ARCH_PXA select ARCH_REQUIRE_GPIOLIB select GENERIC_CLOCKEVENTS select HAVE_SCHED_CLOCK - select TICK_ONESHOT select PLAT_PXA select SPARSE_IRQ help
@@ -668,7 +666,6 @@ config ARCH_SA1100 select GENERIC_CLOCKEVENTS select HAVE_CLK select HAVE_SCHED_CLOCK - select TICK_ONESHOT select ARCH_REQUIRE_GPIOLIB help Support for StrongARM 11x0 based boards.
@@ -1300,7 +1297,6 @@ config HAVE_ARM_SCU config HAVE_ARM_TWD bool depends on SMP - select TICK_ONESHOT help This options enables support for the ARM timer and watchdog unit
Signature · 2 lines
Sent by an employee of the Qualcomm Innovation Center, Inc. The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.