Resolving RCU-scheduler deadlocks

Patent metadata

Field	Value
Publication number	US-8997110-B2
Application number	US-201314093441-A
Country	US
Kind code	B2
Filing date	Nov 30, 2013
Priority date	May 18, 2012
Publication date	Mar 31, 2015
Grant date	Mar 31, 2015

Abstract

A technique for resolving deadlocks between an RCU subsystem and an operating system scheduler. An RCU reader manipulates a counter when entering and exiting an RCU read-side critical section. At the entry, the counter is incremented. At the exit, the counter is manipulated differently depending on the counter value. A first counter manipulation path is taken when the counter indicates a task-context RCU reader is exiting an outermost RCU read-side critical section. This path includes condition-based processing that may result in invocation of the operating system scheduler. The first path further includes a deadlock protection operation that manipulates the counter to prevent an intervening RCU reader from taking the same path. The second manipulation path is taken when the counter value indicates a task-context RCU reader is exiting a non-outermost RCU read-side critical section, or an RCU reader is nested within the first path. This path bypasses the condition-based processing.

First claim

What is claimed is:

1. In a computer system having one or more processors operatively coupled to one or more memory devices and implementing a read-copy update (RCU) subsystem, a method for resolving deadlocks between said RCU subsystem and an operating system scheduler, comprising:
providing an RCU registration component that allows an RCU reader to manipulate an rcu_read_lock_nesting counter when said RCU reader enters an RCU read-side critical section;
providing an RCU unregi…

Assignees

• IBM

Inventors

• Mckenney Paul E

Classifications

• G06F9/524 Primary

  Physics · mapped topic

• G06F9/4881 Primary

  Physics · mapped topic