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Date: Sat, 29 Dec 2012 17:42:45 +0100 From: Frederic Weisbecker <fweisbec@...il.com> To: LKML <linux-kernel@...r.kernel.org> Cc: Frederic Weisbecker <fweisbec@...il.com>, Alessio Igor Bogani <abogani@...nel.org>, Andrew Morton <akpm@...ux-foundation.org>, Chris Metcalf <cmetcalf@...era.com>, Christoph Lameter <cl@...ux.com>, Geoff Levand <geoff@...radead.org>, Gilad Ben Yossef <gilad@...yossef.com>, Hakan Akkan <hakanakkan@...il.com>, Ingo Molnar <mingo@...nel.org>, "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>, Paul Gortmaker <paul.gortmaker@...driver.com>, Peter Zijlstra <peterz@...radead.org>, Steven Rostedt <rostedt@...dmis.org>, Thomas Gleixner <tglx@...utronix.de> Subject: [PATCH 06/27] nohz: Basic full dynticks interface Start with a very simple interface to define full dynticks CPU: use a boot time option defined cpumask through the "full_nohz=" kernel parameter. Make sure you keep at least one CPU outside this range to handle the timekeeping. Also full_nohz= must match rcu_nocb= value. Suggested-by: Paul E. McKenney <paulmck@...ux.vnet.ibm.com> Signed-off-by: Frederic Weisbecker <fweisbec@...il.com> Cc: Alessio Igor Bogani <abogani@...nel.org> Cc: Andrew Morton <akpm@...ux-foundation.org> Cc: Chris Metcalf <cmetcalf@...era.com> Cc: Christoph Lameter <cl@...ux.com> Cc: Geoff Levand <geoff@...radead.org> Cc: Gilad Ben Yossef <gilad@...yossef.com> Cc: Hakan Akkan <hakanakkan@...il.com> Cc: Ingo Molnar <mingo@...nel.org> Cc: Paul E. McKenney <paulmck@...ux.vnet.ibm.com> Cc: Paul Gortmaker <paul.gortmaker@...driver.com> Cc: Peter Zijlstra <peterz@...radead.org> Cc: Steven Rostedt <rostedt@...dmis.org> Cc: Thomas Gleixner <tglx@...utronix.de> --- include/linux/tick.h | 7 +++++++ kernel/time/Kconfig | 9 +++++++++ kernel/time/tick-sched.c | 23 +++++++++++++++++++++++ 3 files changed, 39 insertions(+), 0 deletions(-) diff --git a/include/linux/tick.h b/include/linux/tick.h index 553272e..2d4f6f0 100644 --- a/include/linux/tick.h +++ b/include/linux/tick.h @@ -157,6 +157,13 @@ static inline u64 get_cpu_idle_time_us(int cpu, u64 *unused) { return -1; } static inline u64 get_cpu_iowait_time_us(int cpu, u64 *unused) { return -1; } # endif /* !NO_HZ */ +#ifdef CONFIG_NO_HZ_FULL +int tick_nohz_full_cpu(int cpu); +#else +static inline int tick_nohz_full_cpu(int cpu) { return 0; } +#endif + + # ifdef CONFIG_CPU_IDLE_GOV_MENU extern void menu_hrtimer_cancel(void); # else diff --git a/kernel/time/Kconfig b/kernel/time/Kconfig index 8601f0d..dc6381d 100644 --- a/kernel/time/Kconfig +++ b/kernel/time/Kconfig @@ -70,6 +70,15 @@ config NO_HZ only trigger on an as-needed basis both when the system is busy and when the system is idle. +config NO_HZ_FULL + bool "Full tickless system" + depends on NO_HZ && RCU_USER_QS && VIRT_CPU_ACCOUNTING_GEN && RCU_NOCB_CPU && SMP + select CONTEXT_TRACKING_FORCE + help + Try to be tickless everywhere, not just in idle. (You need + to fill up the full_nohz_mask boot parameter). + + config HIGH_RES_TIMERS bool "High Resolution Timer Support" depends on !ARCH_USES_GETTIMEOFFSET && GENERIC_CLOCKEVENTS diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index ad0e6fa..fac9ba4 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -142,6 +142,29 @@ static void tick_sched_handle(struct tick_sched *ts, struct pt_regs *regs) profile_tick(CPU_PROFILING); } +#ifdef CONFIG_NO_HZ_FULL +static cpumask_var_t full_nohz_mask; +bool have_full_nohz_mask; + +int tick_nohz_full_cpu(int cpu) +{ + if (!have_full_nohz_mask) + return 0; + + return cpumask_test_cpu(cpu, full_nohz_mask); +} + +/* Parse the boot-time nohz CPU list from the kernel parameters. */ +static int __init tick_nohz_full_setup(char *str) +{ + alloc_bootmem_cpumask_var(&full_nohz_mask); + have_full_nohz_mask = true; + cpulist_parse(str, full_nohz_mask); + return 1; +} +__setup("full_nohz=", tick_nohz_full_setup); +#endif + /* * NOHZ - aka dynamic tick functionality */ -- 1.7.5.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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