CODEWITHSUNDEEP
linux-kernelsynchronizationkernel
5h3re3n
5h3re3n

Reputation: 147

What is the difference between rcuc and rcub

What is the difference between rcuc and rcub Kernal threads?

I know that rcu (Read-Copy_Update) is a synchronization mechanism that manages reads and updates simultaneously. https://en.wikipedia.org/wiki/Read-copy-update

And I understand that there are thress main usages for the mechanism:

a. rcu_read_lock() / rcu_read_unlock() rcu_dereference()

b. rcu_read_lock_bh() / rcu_read_unlock_bh() local_bh_disable() / local_bh_enable() rcu_dereference_bh()

c. rcu_read_lock_sched() / rcu_read_unlock_sched() preempt_disable() / preempt_enable() local_irq_save() / local_irq_restore() hardirq enter / hardirq exit NMI enter / NMI exit rcu_dereference_sched()

According to : Blockquotehttps://www.kernel.org/doc/Documentation/RCU/whatisRCU.txt

Yet I didn't find information about rcu{c,b} & when each of these is used, and what "c" and "b" stands for?

Upvotes: 3

Views: 1067

Answers (1)

5h3re3n
5h3re3n

Reputation: 147

ok , found it :

Rename CONFIG_RCU_BOOST_PRIO to CONFIG_RCU_KTHREAD_PRIO and use this value for both the per-CPU kthreads (rcuc/N) and the rcu boosting threads (rcub/n).

http://lkml.iu.edu/hypermail/linux/kernel/1409.2/00514.html

Upvotes: 4

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