Browse Prior Art Database

Multipath Lock Facility Contention Attention Presentation

IP.com Disclosure Number: IPCOM000117096D
Original Publication Date: 1995-Dec-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 34K

Publishing Venue

IBM

Related People

Mannenbach, D: AUTHOR [+2]

Abstract

Disclosed is a method for presenting locking contention attentions to multiple CPUs is a Loosely Coupled environment. The attentions are used to notify current CPUs holding the lock that another CPU has requested exclusive use of the data protected by the lock.

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Multipath Lock Facility Contention Attention Presentation

      Disclosed is a method for presenting locking contention
attentions to multiple CPUs is a Loosely Coupled environment.  The
attentions are used to notify current CPUs holding the lock that
another
CPU has requested exclusive use of the data protected by the lock.

      When using Locking to synchronize access to data through
multiple CPUs in a Loosely Coupled environment it becomes necessary
to notify the current CPUs holding the lock that another CPU has
requested use of the lock in a mode which is not compatible with the
current holders.  The holders of the lock are notified of the
contention for the lock via attention messages.

      In order for lock waiters (CPUs not compatible with the current
holders) to receive access to the data, all holders must receive
contention attentions notifying them to relinquish use of the lock.
To assure that attentions are off-loaded each time contention arises,
the following protocol has been developed.
  1.  Signal Contention whenever the wait queue for a lock goes from
       empty to not empty and the current holder(s) of the lock
       requested contention notification.
  2.  Signal Contention whenever a lock request from the wait queue
is
       granted a lock and not all lock requests on the wait queue can
be
       granted and the current holder(s) of the lock requested
       contention notification.