Am 05.11.2010 00:46, Gilles Chanteperdrix wrote: > Jan Kiszka wrote: >> Am 05.11.2010 00:25, Gilles Chanteperdrix wrote: >>> Jan Kiszka wrote: >>>> Am 04.11.2010 23:08, Gilles Chanteperdrix wrote: >>>>> Jan Kiszka wrote: >>>>>> rework. Safer for now is likely to revert 56ff4329ff, keeping nucleus >>>>>> debugging off. >>>>> That is not enough. >>>> It is, I've reviewed the code today. >>> The fallouts I am talking about are: >>> 47dac49c71e89b684203e854d1b0172ecacbc555 >> >> Not related. >> >>> 38f2ca83a8e63cc94eaa911ff1c0940c884b5078 >> >> An optimization. >> >>> 5e7cfa5c25672e4478a721eadbd6f6c5b4f88a2f >> >> That fall out of that commit is fixed in my series. >> >>>>> This commit was followed by several others to "fix >>>>> the fix". You know how things are, someone proposes a fix, which fixes >>>>> things for him, but it breaks in the other people configurations (one of >>>>> the fallouts was a complete revamp of include/asm-arm/atomic.h for >>>>> instance). >>>>> >>>> I've pushed a series that reverts that commit, then fixes and cleans up >>>> on top of it. Just pushed if you want to take a look. We can find some >>>> alternative debugging mechanism independently (though I'm curious to see >>>> it - it still makes no sense to me). >>> Since the fix is simply a modification to what we have currently. I >>> would prefer if we did not remove it. In fact, I think it would be >>> simpler if we started from what we currently have than reverting past >>> patches. >> >> Look at the series, it goes step by step to an IMHO clean state. We can >> pull out the debugging check removal, though, if you prefer to work on >> top of the existing code. > > From my point of view, Anders looks for something that works, so > following the rules that the minimal set of changes minimize the chances > of introducing new bugs while cleaning, I would go for the minimal set > of changes, such as:
I don't mind where to start, you need to understand the code anyway to
asses any change, may it be a complete rewrite, revert and then rework,
or a combination like below.
>
> diff --git a/include/nucleus/sched.h b/include/nucleus/sched.h
> index df56417..8150510 100644
> --- a/include/nucleus/sched.h
> +++ b/include/nucleus/sched.h
> @@ -165,28 +165,27 @@ struct xnsched_class {
> #endif /* CONFIG_SMP */
>
> /* Test all resched flags from the given scheduler mask. */
> -static inline int xnsched_resched_p(struct xnsched *sched)
> +static inline int xnsched_remote_resched_p(struct xnsched *sched)
> {
> - return testbits(sched->status, XNRESCHED);
> + return !xnarch_cpus_empty(current_sched->resched);
> }
>
> -static inline int xnsched_self_resched_p(struct xnsched *sched)
> +static inline int xnsched_resched_p(struct xnsched *sched)
> {
> return testbits(sched->status, XNRESCHED);
> }
>
> /* Set self resched flag for the given scheduler. */
> #define xnsched_set_self_resched(__sched__) do { \
> - setbits((__sched__)->status, XNRESCHED); \
> + __setbits((__sched__)->status, XNRESCHED); \
> } while (0)
>
> /* Set specific resched flag into the local scheduler mask. */
> #define xnsched_set_resched(__sched__) do { \
> xnsched_t *current_sched = xnpod_current_sched(); \
> - setbits(current_sched->status, XNRESCHED); \
> + __setbits(current_sched->status, XNRESCHED);
> \
> if (current_sched != (__sched__)) { \
> xnarch_cpu_set(xnsched_cpu(__sched__), current_sched->resched);
> \
> - setbits((__sched__)->status, XNRESCHED);
> \
> } \
> } while (0)
>
> diff --git a/ksrc/nucleus/pod.c b/ksrc/nucleus/pod.c
> index 862838c..4cb707a 100644
> --- a/ksrc/nucleus/pod.c
> +++ b/ksrc/nucleus/pod.c
> @@ -276,18 +276,16 @@ EXPORT_SYMBOL_GPL(xnpod_fatal_helper);
>
> void xnpod_schedule_handler(void) /* Called with hw interrupts off. */
> {
> - xnsched_t *sched;
> + xnsched_t *sched = xnpod_current_sched();
>
> trace_mark(xn_nucleus, sched_remote, MARK_NOARGS);
> #if defined(CONFIG_SMP) && defined(CONFIG_XENO_OPT_PRIOCPL)
> - sched = xnpod_current_sched();
> if (testbits(sched->status, XNRPICK)) {
> clrbits(sched->status, XNRPICK);
> xnshadow_rpi_check();
> }
> -#else
> - (void)sched;
> #endif /* CONFIG_SMP && CONFIG_XENO_OPT_PRIOCPL */
> + xnsched_set_self_resched(sched);
> xnpod_schedule();
> }
>
> @@ -2174,7 +2172,7 @@ static inline int __xnpod_test_resched(struct xnsched
> *sched)
> int resched = testbits(sched->status, XNRESCHED);
> #ifdef CONFIG_SMP
> /* Send resched IPI to remote CPU(s). */
> - if (unlikely(xnsched_resched_p(sched))) {
> + if (unlikely(xnsched_remote_resched_p(sched))) {
> xnarch_send_ipi(sched->resched);
> xnarch_cpus_clear(sched->resched);
> }
> diff --git a/ksrc/nucleus/timer.c b/ksrc/nucleus/timer.c
> index 1fe3331..a0ac627 100644
> --- a/ksrc/nucleus/timer.c
> +++ b/ksrc/nucleus/timer.c
> @@ -97,7 +97,7 @@ void xntimer_next_local_shot(xnsched_t *sched)
> __clrbits(sched->status, XNHDEFER);
> timer = aplink2timer(h);
> if (unlikely(timer == &sched->htimer)) {
> - if (xnsched_self_resched_p(sched) ||
> + if (xnsched_resched_p(sched) ||
> !xnthread_test_state(sched->curr, XNROOT)) {
> h = xntimerq_it_next(&sched->timerqueue, &it, h);
> if (h) {
>
>
This looks correct. The next steps on top would then be
- avoid local reschedule if only remotes need to be signaled
- remaining conversions to non-atomic status access
- UP optimization
Jan
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