Messages in this thread | | | Date | Wed, 29 Aug 2018 15:20:21 -0700 | From | "Paul E. McKenney" <> | Subject | [PATCH tip/core/rcu 0/19] RCU flavor-consolidation changes for v4.20/v5.0 |
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Hello!
This series contains the RCU flavor consolidation, along with some initial cleanup work enabled by that consolidation (and some that became apparent while cleaning up):
1. Refactor rcu_{nmi,irq}_{enter,exit}(), saving a branch on the idle entry/exit hotpaths, courtesy of Byungchul Park,
2. Defer reporting RCU-preempt quiescent states when disabled. This is the key commit that consolidates the RCU-bh and RCU-sched flavors into RCU, however, the RCU-bh and RCU-sched flavors still exist independently as well at this point.
3. Test extended "rcu" read-side critical sections. This commit causes rcutorture to test RCU's new-found ability to act as the combination of RCU, RCU-bh, and RCU-sched.
4. Allow processing deferred QSes for exiting RCU-preempt readers. This is a optimization.
5. Remove now-unused ->b.exp_need_qs field from the rcu_special union.
6. Add warning to detect half-interrupts. Test the claim that the Linux kernel no longer does half-interrupts.
7. Apply RCU-bh QSes to RCU-sched and RCU-preempt when safe, that is, make the consolidated RCU inherit RCU-bh's denial-of-service avoidance mechanism.
8. Report expedited grace periods at context-switch time. This is an optimization enabled by the RCU flavor consolidation.
9. Define RCU-bh update API in terms of RCU. This commit gets rid of the RCU-bh update mechanism.
10. Update comments and help text to account for the removal of the RCU-bh update mechanism.
11. Drop "wake" parameter from rcu_report_exp_rdp().
12. Fix typo in rcu_get_gp_kthreads_prio() header comment.
13. Define RCU-sched API in terms of RCU for Tree RCU PREEMPT builds. Although this commit gets rid of the RCU-sched update mechanism from PREEMPT builds, it of course remains as the sole RCU flavor for !PREEMPT && !SMP builds.
14. Express Tiny RCU updates in terms of RCU rather than RCU-sched. This will enable additional cleanups and code savings.
15. Remove RCU_STATE_INITIALIZER() in favor of just using an open-coded initializer for the sole remaining rcu_state structure.
16. Eliminate rcu_state structure's ->call field, as it is now always just call_rcu().
17. Remove rcu_state structure's ->rda field, as there is now only one set of per-CPU rcu_data structures.
Thanx, Paul
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Documentation/RCU/Design/Requirements/Requirements.html | 50 - include/linux/rcupdate.h | 48 - include/linux/rcupdate_wait.h | 6 include/linux/rcutiny.h | 61 + include/linux/rcutree.h | 31 include/linux/sched.h | 6 kernel/rcu/Kconfig | 10 kernel/rcu/rcutorture.c | 1 kernel/rcu/tiny.c | 163 +-- kernel/rcu/tree.c | 655 +++++----------- kernel/rcu/tree.h | 44 - kernel/rcu/tree_exp.h | 256 +++--- kernel/rcu/tree_plugin.h | 523 ++++++------ kernel/rcu/update.c | 2 kernel/softirq.c | 3 15 files changed, 836 insertions(+), 1023 deletions(-)
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