Quickly reacquirable locks

Techniques are provided for quickly reacquiring mutual exclusion locks (QRLs), such as in the case in which a single process repeatedly acquires and releases the lock and in which no other process attempts to acquire the same lock. When the first holder of a QRL first acquires the lock, it biases th...

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Bibliographic Details
Main Authors Dice, David, Moir, Mark S, Scherer, III, William N
Format Patent
LanguageEnglish
Published 12.10.2010
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Summary:Techniques are provided for quickly reacquiring mutual exclusion locks (QRLs), such as in the case in which a single process repeatedly acquires and releases the lock and in which no other process attempts to acquire the same lock. When the first holder of a QRL first acquires the lock, it biases the lock to itself. Bias may be directed in different way or at different times in some realizations. Biasing may involve a one-time compare-and-swap instruction. Thereafter, this bias-holder can reacquire and release the lock free of atomic read-modify-write operations. If a second process attempts to acquire a QRL, then the lock may revert to a "default lock". Any standard mutual exclusion lock may be used as the default lock. A QRL lock may be reinitialized so that it can be rebiased. Rebiasing may be valuable in the case of migratory data access patterns.