aboutsummaryrefslogtreecommitdiffstats
path: root/Documentation/RCU/Design (follow)
AgeCommit message (Collapse)AuthorFilesLines
2016-06-14documentation: Add RCU_NONIDLE() restrictions to requirementsPaul E. McKenney1-0/+35
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2016-04-19documentation: Add documentation for RCU's major data structuresPaul E. McKenney12-0/+8291
This commit adds documentation for RCU's major data structures, including rcu_state, rcu_node, rcu_data, rcu_dynticks, and rcu_head. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2016-03-31documentation: Emphasize the call_rcu() is illegal from idlePaul E. McKenney1-1/+1
Although call_rcu()'s fastpath works just fine on an idle CPU, some branches of the slowpath invoke the scheduler, which uses RCU. Therefore, this commit emphasizes the fact that call_rcu() must not be invoked from an idle CPU. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2016-03-31documentation: Sharpen up the no-readers quick quizPaul E. McKenney1-5/+8
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2016-03-31documentation: Get rid of duplicate .htmlx filePaul E. McKenney3-3441/+428
This commit uses colors to obscure the quick-quiz answers, thus getting rid of the .htmlx file. Use your mouse to select the answer in order to see the text. Alternatively, use your favorite scripting language to remove all occurences of "<font color="ffffff">" from the file. Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2016-03-31documentation: Remove unnecessary images from requirementsPaul E. McKenney4-253/+40
This commit removes a cutesy cartoon and also a diagram that can just as easily be represented by text. Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2016-03-31documentation: Document illegality of call_rcu() from offline CPUsPaul E. McKenney2-2/+4
There is already a blanket statement about no member of RCU's API being legal from an offline CPU, but add an explicit note where it states that it is illegal to invoke call_rcu() from an NMI handler. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2016-03-31documentation: Explain why rcu_read_lock() needs no barrier()Paul E. McKenney2-43/+115
This commit adds a Quick Quiz whose answer explains why the compiler code reordering enabled by CONFIG_PREEMPT=n's empty rcu_read_lock() and rcu_read_unlock() functions does not hinder RCU's ability to figure out which RCU read-side critical sections have completed and not. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2016-03-31documentation: Add synchronize_rcu_mult() to the requirementsPaul E. McKenney2-0/+174
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2016-03-31documentation: Add real-time requirements from CPU-bound workloadsPaul E. McKenney2-1/+17
This commit records RCU's responsibility to avoid degrading latencies of CPUs running tight loops within properly configured workloads, both in kernel and in userspace. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2015-12-05documentation: Update RCU requirements based on expedited changesPaul E. McKenney2-3/+19
Because RCU-sched expedited grace periods now use IPIs and interact with rcu_read_unlock(), it is no longer sufficient to disable preemption across RCU read-side critical sections that acquire and hold scheduler locks. It is now necessary to instead disable interrupts. This commit documents this change. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2015-12-05documentation: Clarify RCU memory barriers and requirementsPaul E. McKenney2-54/+78
The RCU requirements do not make it absolutely clear that the memory-barrier requirements are not intended to replace the fundamental requirement that all pre-existing RCU readers complete before a grace period completes. This commit therefore pulls the memory-barrier requirements into a separate section and explicitly calls out the relationship between the memory-barrier requirements and the fundamental requirement. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2015-12-05documentation: Expand on scheduler/RCU deadlock requirementsPaul E. McKenney2-10/+18
This commit adds a second option for avoiding scheduler/RCU deadlocks, namely that preemption be disabled across the entire RCU read-side critical section in question. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2015-12-05documentation: Composability analogiesPaul E. McKenney2-0/+16
This commit expands on RCU's composability by comparing it to that of transactional memory and of locking. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2015-12-05documentation: Cover requirements controlling stall warningsPaul E. McKenney2-2/+48
This commit adds verbiage on boot and sysfs parameters that can be used to control RCU CPU stall warnings, both to change the timeout and to suppress these warnings entirely. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2015-12-05Documentation: Record bottom-bit-zero guarantee for ->nextPaul E. McKenney2-0/+86
This commit records RCU's guarantee that the bottom bit of the rcu_head structure's ->next field will remain zero for callbacks posted via call_rcu(), but not necessarily for <tt>kfree_rcu()</tt> or some possible future call_rcu_lazy() variant that might one day be created for energy-efficiency purposese. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> [ paulmck: Updates URLs as suggested by Josh Triplett. ]
2015-12-05documentation: Record RCU requirementsPaul E. McKenney7-0/+6800
This commit adds RCU requirements as published in a 2015 LWN series. Bringing these requirements in-tree allows them to be updated as changes are discovered. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> [ paulmck: Updates to charset and URLs as suggested by Josh Triplett. ]
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.