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 */
-
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