one? • implementation status 2.TS2 Hazard Pointer • how I learn to love C++ tricks ### 3. TS2 RCU • From C to C++ in 2500 days ![Image](/uploads/documents/f/0/f/6/f0f673cc15de005f5c335ee7edeab6dd/p3_1 Barriers: Adapted into C++ 20 • Atomic smart pointers: Adapted into C++17 ## Talking about HP and RCU since 2014 1\. Erwin Schrödinger’s Zoo and Werner Heisenberg’s advice 2. Increase uncertainty to primitives for locked-free programming on concurrent data structures. These are cell, hazard ptr and RCU. These extend the existing shared_ptr and the proposed atomic_shared_ptr which all have safe reclamation

cost as C. This can be checked only once on the constructor. ## Branded types: locking patterns, RCU struct Process: exists 'a { inner: SpinLock<'a, ProcessInner>, mm: RcuPointer<'a Option>>>, } fn read(process: &Process) { let rcu_guard = rcu::read_lock(); let mm = process.mm.get(&rcu_guard); } fn write(process: &Process) { let old; { old = process.mm.swap(None, &guard); } // `drop` for `old` calls `synchronize_rcu` } ## Function context restrictions (“colored unsafe”) Atomic vs. sleepable context

>Oct200:00 [rcu_gp]root40.00.000 ?I<Oct200:00 [rcu_par_gp]IOct202:17 [rcu_sched]root110.00.000 ?IOct200:00 [rcu_bh]

0 码力 | 30 页 | 1.29 MB | 2 年前

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3e89b37f8/0 root=UUID=56731f4f-f558-46a3-85d3-d1b579683385 rw rootflags=prjquota skew_tick=1 nohz=on rcu_nocbs=3-5 tuned.non_isolcpus=ffffffc7 intel_pstate=disable 第 第 15 章 章 为 为平台 平台验证执 验证执行延 行延迟测试 迟测试 id=openstack root=UUID=5a4ddf16-9372-44d9-ac4e- 3ee329e16ab3 rw rootflags=prjquota skew_tick=1 nohz=on rcu_nocbs=1-3 tuned.non_isolcpus=000000ff,ffffffff,ffffffff,fffffff1 intel_pstate=disable nosoftlockup id=openstack root=UUID=5a4ddf16-9372-44d9-ac4e- 3ee329e16ab3 rw rootflags=prjquota skew_tick=1 nohz=on rcu_nocbs=1-3 tuned.non_isolcpus=000000ff,ffffffff,ffffffff,fffffff1 intel_pstate=disable nosoftlockup

e_uid; kgid_t e_gid; }; }; struct posix_acl { refcount_t a_refcount; struct rcu_head a_rcu; unsigned int a_count; struct posix_acl_entry a_entries[0]; }; ## 内存中的ACL 是如何与具体的 Inode

r>7 root20 0000 S 0.0 0.00:00.02 rcu_sched... You can also use the ps command root720800 -0rcu_gp22:02 ?00:00:00[rcu sched]

[kworker/0:0H] root 6 0.0 0.0 0 0 ? S May29 0:11 [ksoftirqd/0] root 7 0.0 0.0 0 0 ? S May29 8:27 [rcu_sched] ... long output You can see that the output also tells you under which user the process is 00 kworker/0:0H 6 root 20 0 0 0 0 S 0.0 0.0 0:11.79 ksoftirqd/0 7 root 20 0 0 0 0 S 0.0 0.0 8:28.06 rcu_sched ... long output By the way, feel free to press 1 and see if anything changes in the top command

000?SMay298:27[rcu_sched]rcu_sched ... long output By the way, feel free to press 1 and see if anything changes in the top command

implementation of the C++ Concurrency TS, including a lock-free implementation of atomic_shared_ptr and RCU. http://stdthread.co.uk

unprotected garbage that has accumulated ## Common implementations: • Hazard pointers (Concurrency TS2) • RCU (Concurrency TS2) Carnegie Mellon University ## Solution #3: Deferred reclamation ## Correct: