Russell, On Mon, 8 Apr 2013, Russell King - ARM Linux wrote: > On Mon, Mar 25, 2013 at 03:02:39PM +0100, Thomas Gleixner wrote: > So, how can I review these changes when all there is is a git URL, and > I *do* not want to pull them into my tree without first looking at the > patches, possibly reviewing them and *replying* with the patch inline? the patches were CC'ed to LKML and linux-arch and I expected that you are at least having the latter. Find the relevant patch inlined below. > I see you've now added this stuff to -tip. I guess ARM doesn't matter > to you at all. I guess having ARM people review the core changes doesn't > matter either. > > Well, I guess if it's broken, we'll just have to fix it up after the > merge window. > > One rule for x86, a different one for ARM. Let x86 maintainers moan > about ARM people, but don't let ARM people moan about x86 maintainers. > Yes, sure, right, I get it. Sigh no. > So, explicitly, my concern is this replacement of enable_hlt()/disable_hlt() > with this cpu_idle_poll_ctrl(), and whether this interface is still > counted - so that it's possible to call disable_hlt() to _permanently_ > disable any hlt-based idle loop. It is a counter. I looked carefully at all the various slightly differently fcked up implementations and picked the counter based one as it fits all requirements. Thanks, tglx --- Subject: idle: Implement generic idle function From: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Date: Thu, 21 Mar 2013 22:49:35 +0100 All idle functions in arch/* are more or less the same, plus minus a few bugs and extra instrumentation, tickless support and other optional items. Implement a generic idle function which resembles the functionality found in arch/. Provide weak arch_cpu_idle_* functions which can be overridden by the architecture code if needed. Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx> Cc: Paul McKenney <paulmck@xxxxxxxxxxxxxxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Reviewed-by: Cc: Srivatsa S. Bhat <srivatsa.bhat@xxxxxxxxxxxxxxxxxx> Cc: Magnus Damm <magnus.damm@xxxxxxxxx> Link: http://lkml.kernel.org/r/20130321215233.646635455@xxxxxxxxxxxxx Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> --- arch/Kconfig | 3 + include/linux/cpu.h | 8 +++ kernel/cpu/idle.c | 105 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 116 insertions(+) Index: linux-2.6/arch/Kconfig =================================================================== --- linux-2.6.orig/arch/Kconfig +++ linux-2.6/arch/Kconfig @@ -216,6 +216,9 @@ config USE_GENERIC_SMP_HELPERS config GENERIC_SMP_IDLE_THREAD bool +config GENERIC_IDLE_LOOP + bool + # Select if arch init_task initializer is different to init/init_task.c config ARCH_INIT_TASK bool Index: linux-2.6/include/linux/cpu.h =================================================================== --- linux-2.6.orig/include/linux/cpu.h +++ linux-2.6/include/linux/cpu.h @@ -220,4 +220,12 @@ enum cpuhp_state { void cpu_startup_entry(enum cpuhp_state state); void cpu_idle(void); +void cpu_idle_poll_ctrl(bool enable); + +void arch_cpu_idle(void); +void arch_cpu_idle_prepare(void); +void arch_cpu_idle_enter(void); +void arch_cpu_idle_exit(void); +void arch_cpu_idle_dead(void); + #endif /* _LINUX_CPU_H_ */ Index: linux-2.6/kernel/cpu/idle.c =================================================================== --- linux-2.6.orig/kernel/cpu/idle.c +++ linux-2.6/kernel/cpu/idle.c @@ -3,8 +3,113 @@ */ #include <linux/sched.h> #include <linux/cpu.h> +#include <linux/tick.h> +#include <linux/mm.h> +#include <asm/tlb.h> + +#include <trace/events/power.h> + +#ifndef CONFIG_GENERIC_IDLE_LOOP void cpu_startup_entry(enum cpuhp_state state) { cpu_idle(); } +#else + +static int __read_mostly cpu_idle_force_poll; + +void cpu_idle_poll_ctrl(bool enable) +{ + if (enable) { + cpu_idle_force_poll++; + } else { + cpu_idle_force_poll--; + WARN_ON_ONCE(cpu_idle_force_poll < 0); + } +} + +#ifdef CONFIG_GENERIC_IDLE_POLL_SETUP +static int __init cpu_idle_poll_setup(char *__unused) +{ + cpu_idle_force_poll = 1; + return 1; +} +__setup("nohlt", cpu_idle_poll_setup); + +static int __init cpu_idle_nopoll_setup(char *__unused) +{ + cpu_idle_force_poll = 0; + return 1; +} +__setup("hlt", cpu_idle_nopoll_setup); +#endif + +static inline int cpu_idle_poll(void) +{ + trace_cpu_idle_rcuidle(0, smp_processor_id()); + local_irq_enable(); + while (!need_resched()) + cpu_relax(); + trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, smp_processor_id()); + return 1; +} + +/* Weak implementations for optional arch specific functions */ +void __weak arch_cpu_idle_prepare(void) { } +void __weak arch_cpu_idle_enter(void) { } +void __weak arch_cpu_idle_exit(void) { } +void __weak arch_cpu_idle_dead(void) { } +void __weak arch_cpu_idle(void) +{ + cpu_idle_force_poll = 1; +} + +/* + * Generic idle loop implementation + */ +static void cpu_idle_loop(void) +{ + while (1) { + tick_nohz_idle_enter(); + + while (!need_resched()) { + check_pgt_cache(); + rmb(); + + if (cpu_is_offline(smp_processor_id())) + arch_cpu_idle_dead(); + + local_irq_disable(); + arch_cpu_idle_enter(); + + if (cpu_idle_force_poll) { + cpu_idle_poll(); + } else { + current_clr_polling(); + if (!need_resched()) { + stop_critical_timings(); + rcu_idle_enter(); + arch_cpu_idle(); + WARN_ON_ONCE(irqs_disabled()); + rcu_idle_exit(); + start_critical_timings(); + } else { + local_irq_enable(); + } + current_set_polling(); + } + arch_cpu_idle_exit(); + } + tick_nohz_idle_exit(); + schedule_preempt_disabled(); + } +} + +void cpu_startup_entry(enum cpuhp_state state) +{ + current_set_polling(); + arch_cpu_idle_prepare(); + cpu_idle_loop(); +} +#endif -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
