Lines Matching refs:grace
13 grace-period memory ordering guarantee is provided.
18 RCU grace periods provide extremely strong memory-ordering guarantees
20 Any code that happens after the end of a given RCU grace period is guaranteed
21 to see the effects of all accesses prior to the beginning of that grace
23 Similarly, any code that happens before the beginning of a given RCU grace
25 of that grace period that are within RCU read-side critical sections.
34 two phases, one of which is executed before the grace period and
35 the other of which is executed after the grace period.
49 The workhorse for RCU's grace-period memory ordering is the
73 network among all CPUs that were in any way involved in the grace
75 the grace period in question.
116 RCU's grace-period memory ordering guarantee to extend to any
123 The grace-period kthread invokes ``rcu_dynticks_snap()`` and
130 | But what about CPUs that remain offline for the entire grace period? |
134 | Such CPUs will be offline at the beginning of the grace period, so |
135 | the grace period won't expect quiescent states from them. Races |
136 | between grace-period start and CPU-hotplug operations are mediated |
143 a CPU that is not yet aware that the grace period has ended, and thus
144 might not yet be subject to the grace period's memory ordering.
164 Tree RCU's grace--period memory-ordering guarantees rely most heavily on
169 newly arrived RCU callbacks against future grace periods:
230 Tree RCU's grace-period memory-ordering guarantee is provided by a
248 If RCU's grace-period guarantee is to mean anything at all, any access
250 happen before the corresponding grace period. The implementation of this
251 portion of RCU's grace period guarantee is shown in the following
260 structure on a per-CPU list, which cannot become associated with a grace
277 There are a few other code paths within grace-period processing that
280 with a future grace-period number under the protection of the CPU's lead
289 update) happen before the start of the corresponding grace period.
306 Grace-period initialization is carried out by the grace-period kernel
309 ordering through the grace-period computation will require duplicating
312 to keep the ``rcu_node`` river tractable, the grace-period kernel
314 section with the various phases of grace-period initialization.
316 The first ordering-related grace-period initialization action is to
317 advance the ``rcu_state`` structure's ``->gp_seq`` grace-period-number
328 grace period. In the common case where the number of online CPUs for
352 ``__note_gp_changes()`` to notice that a new grace period has started,
353 as described in the next section. But because the grace-period kthread
354 started the grace period at the root (with the advancing of the
357 the start of the grace period will happen after the actual start of the
358 grace period.
363 | But what about the CPU that started the grace period? Why wouldn't it |
364 | see the start of the grace period right when it started that grace |
370 | CPU starting the grace period is immediately aware of having done so. |
372 | the CPU starting the grace period does not really become aware of the |
373 | start of this grace period until its first call to |
383 When all entities that might block the grace period have reported
385 states reported on their behalf), the grace period can end. Online
392 end of the grace period. Earlier quiescent states would push up the
400 point that CPU will notice the start of a new grace period while holding
402 diagram happens after the start of the grace period. In addition, this
405 grace period, and thus a critical section that the grace period must
412 | beginning of the grace period (the advancing of ``->gp_seq`` from |
413 | earlier), so why should the grace period wait on such a critical |
418 | It is indeed not necessary for the grace period to wait on such a |
421 | more scalable than a “big bang” all-at-once grace-period start could |
437 apply to the current grace period, it invokes ``rcu_report_rnp()`` which
466 The RCU grace-period kernel thread samples the per-CPU idleness variable
470 will happen before the end of the current grace period. Similarly, the
471 beginning of the current grace period will happen before any RCU
475 Plumbing this into the full grace-period execution is described
492 ``->qsmaskinitnext``. The RCU grace-period kernel thread samples this
494 grace period.
496 Plumbing this into the full grace-period execution is described
503 states, and therefore the grace-period kernel thread must do the
525 | subordinate to that structure on which the current grace period is |
527 | root ended the grace period? |
548 As indicated by the oval at the bottom of the diagram, once grace-period
549 cleanup is complete, the next grace period can begin.
554 | But when precisely does the grace period end? |
558 | There is no useful single point at which the grace period can be said |
573 waiting for this grace period to end. These callbacks are identified by
590 which preserves the required ordering against the newly completed grace
598 important, consider the top half of the `grace-period
602 the rightmost leaf ``rcu_node`` structure, and the grace-period kernel
604 grace period's memory ordering might not yet have reached that CPU, so