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Set Storage Protect Key Buffer Disclosure Number: IPCOM000054326D
Original Publication Date: 1980-Jan-01
Included in the Prior Art Database: 2005-Feb-13

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Pomerene, JH Rechtschaffen, RN [+details]


Currently the set storage protect key (SSK) instruction takes approximately 100 cycles during which no concurrent activity is possible within the processing unit. The reason for the long execution time is that the Translation Look Aside Buffer (TLB) must be cycled through so that entries which correspond to the associated 2K block can be updated (or invalidated) and the access exceptions for subsequent instruction will be consistent with the new storage protect key. This cycling can be accomplished as easily in parallel for multiple SSK instructions as for a single one. An SSK-buffer which maintain unprocessed key updates allows for multiple parallel updating when full or during a serializing instruction such as Start Input-Output (SIO) which does not use the TLB.