Messages in this thread | | | Date | Thu, 8 Sep 2005 15:08:54 -0700 | From | Nishanth Aravamudan <> | Subject | Re: [PATCH 1/3] dynticks - implement no idle hz for x86 |
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On 08.09.2005 [14:22:13 -0700], Nishanth Aravamudan wrote: > On 08.09.2005 [13:00:36 +0300], Tony Lindgren wrote: > > * Nishanth Aravamudan <nacc@us.ibm.com> [050907 18:07]: > > > On 07.09.2005 [10:37:43 +0300], Tony Lindgren wrote: > > > > * Nishanth Aravamudan <nacc@us.ibm.com> [050905 20:02]: > > > > > On 05.09.2005 [10:27:05 +0300], Tony Lindgren wrote: > > > > > > * Srivatsa Vaddagiri <vatsa@in.ibm.com> [050905 10:03]: > > > > > > > On Sun, Sep 04, 2005 at 01:10:54PM -0700, Nishanth Aravamudan wrote: > > > > > > > > > > > > > > > > Also, I am a bit confused by the use of "dynamic-tick" to describe these > > > > > > > > changes. To me, these are all NO_IDLE_HZ implementations, as they are > > > > > > > > only invoked from cpu_idle() (or their equivalent) routines. I know this > > > > > > > > is true of s390 and the x86 code, and I believe it is true of the ARM > > > > > > > > code? If it were dynamic-tick, I would think we would be adjusting the > > > > > > > > timer interrupt frequency continuously (e.g., at the end of > > > > > > > > __run_timers() and at every call to {add,mod,del}_timer()). I was > > > > > > > > working on a patch which did some renaming to no_idle_hz_timer, etc., > > > > > > > > but it's mostly code churn :) > > > > > > > > > > > > > > Yes, the name 'dynamic-tick' is misleading!
<snipping much useful feedback and many constructive conversations>
So, after *all* that, I'm going back to dyntick (notice no hyphen though :-P). Everyone ok with this doc?
Thanks, Nish
- include/linux/dyntick.h with definitions in kernel/dyntick.c
#define DYN_TICK_ENABLED (1 << 1) #define DYN_TICK_SUITABLE (1 << 0)
#define DYN_TICK_MIN_SKIP 2
/* Abstraction of a dynamic tick source * @state: current state * @max_skip: current maximum number of jiffies to program h/w to skip * @min_skip: current minimum number of jiffies to program h/w 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 * @reprogram: actually interact with h/w, return number of ticks the * h/w will skip * @recover_time: handler for returning from skipped ticks and keeping * time consistent * @enter_all_cpus_idle: last cpu to go idle calls this, which should * disable any timer source (e.g. PIT on x86) * @exit_all_cpus_idle: first cpu to wake after @enter_all_cpus_idle has * been called should use this to revert the * effects of that function */ struct dyntick_timer { unsigned int state; unsigned long max_skip; unsigned long min_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 (*enter_all_cpus_idle) (int); void (*exit_all_cpus_idle) (int); spinlock_t lock; };
extern void dyntick_timer_register(struct dyntick_timer *new_dyntick_timer); /* so do we need this? Maybe it can just be static to dyntick.c and all the callable functions will call-down to the structure members? */ extern struct dyntick_timer *current_dyntick_timer;
#ifdef CONFIG_NO_IDLE_HZ /* which means CONFIG_DYNTICK is also on */ extern void set_dyntick_max_skip(unsigned long max_skip); extern void set_dyntick_min_skip(unsigned long min_skip); /* return number of ticks skipped, as we can request any number called from cpu_idle() in dyntick-enabled arch's */ extern unsigned long reprogram_dyntick(void);
extern struct tick_source * __init arch_select_tick_source(void); /* calls select_tick_source(), then calls tick_source_register() */ extern void __init dyn_tick_init(void);
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/dyntick.h>
- timer.c / timer.h /* moved from sched.c/.h */ cpumask_t no_idle_hz_cpumask;
- each arch-specific file pair needs to provide: arch_select_tick_source(); an appropriate struct tick_source definitions, functions, etc. per usable h/w
- include/asm-i386/dyntick.h with defines in arch/i386/dyntick.c /* basically already done */
- include/asm-arm/arch-omap/dyntick.h with definitions in arch/arm/mach-omap/dyntick.c
- include/asm-s390/dyntick.h with definitions in arch/s390/dyntick.c
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