On 07.09.2005 [11:13:04 +0300], Tony Lindgren wrote: > * Nishanth Aravamudan <[EMAIL PROTECTED]> [050906 23:55]: > > ... > > > Sigh, later than I had hoped, but here is what I have hashed out so far. > > Does it seem like a step in the right direction? Rather hand-wavy, but I > > think it's mostly correct ;) > > Some comments below.
Updated document below. Thanks, Nish - include/linux/timer.h with definitions in kernel/timer.c OR better in - include/linux/ticksource.h with definitions in kernel/ticksource.c? #define DYN_TICK_ENABLED (1 << 1) #define DYN_TICK_SUITABLE (1 << 0) #define DYN_TICK_MIN_SKIP 2 /* Abstraction of a tick source * @state: current state * @max_skip: current maximum number of ticks to skip * @init: initialization routine * @enable_dyn_tick: called via sysfs to enable interrupt skipping * @disable_dyn_tick: called via sysfs to disable interrupt * skipping * @set_all_cpus_idle: last cpu to go idle calls this, which should * disable any timesource (e.g. PIT on x86) * @recover_time: handler for returning from skipped ticks and keeping * time consistent */ struct tick_source { unsigned int state; unsigned long max_skip; int (*init) (void); void (*enable_dyn_tick) (void); void (*disable_dyn_tick) (void); unsigned long (*reprogram) (unsigned long); /* return number of ticks skipped */ unsigned long (*recover_time) (int, void *, struct pt_regs *); /* handler in arm */ /* following empty in UP */ void (*set_all_cpus_idle) (int); spinlock_t lock; }; extern void tick_source_register(struct tick_source *new_tick_source); extern struct tick_source *current_ticksource; #ifdef CONFIG_NO_IDLE_HZ /* which means CONFIG_DYNTICK is also on */ extern void set_tick_max_skip(unsigned long max_skip); /* idle_reprogram_tick calls reprogram_tick calls current_ticksource->reprogram() * do we really need the first step? */ extern void idle_reprogram_tick(void); /* return number of ticks skipped, potentially for accounting purposes? */ extern unsigned long reprogram_tick(void); extern struct tick_source * __init arch_select_tick_source(void); extern void __init dyn_tick_init(void); /* calls select_tick_source(), verifies source is usable, then calls tick_source_register() */ static inline int dyn_tick_enabled(void) { return (current_ticksource->state & DYN_TICK_ENABLED); } #else /* CONFIG_NO_IDLE_HZ */ static inline void set_tick_max_skip(unsigned long max_skip) { } static inline void idle_reprogram_tick(void) { } static inline unsigned long reprogram_tick(void) { return 0; } static inline void dyn_tick_init(void) { } static inline int dyn_tick_enabled(void) { return 0; } #endif /* CONFIG_NO_IDLE_HZ */ /* Pick up arch specific header */ #include <asm/timer.h> /* or <asm/ticksource.h>, depending */ - sched.c / sched.h /* do we want these elsewhere? */ cpumask_t no_idle_hz_cpumask; - each arch-specific file pair needs to provide: arch_select_tick_source(); appropriate struct tick_source definitions, functions, etc. - include/asm-i386/timer.h /* or ticksource.h */ with defines in arch/i386/timer.c /* or ticksource.c */ - include/asm-arm/arch-omap/timer.h /* or ticksource.h */ with definitions in arch/arm/mach-omap/timer.c /* or ticksource.c */ - include/asm-s390/timer.h /* or ticksource.h */ with definitions in arch/s390/timer.c /* or ticksource.c */ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/