International Business Machines Corporation

Qimonda Ag

Johannes C Reichart

Christian Jacobi

Anthony Saporito

Ulrich Mayer

Markus Kaltenbach

Martin Recktenwald

Markus Helms

Siegmund Schlechter

Aaron Tsai

Gerrit Koch

Ralf Winkelmann

Carsten Greiner

Dietmar Schmunkamp

Simon H Friedmann

Peter Gregorius

Manfred Berroth

Markus Groezing

Disclosed herein is a virtual cache and method in a processor for supporting multiple threads on the same cache line. The processor is configured to support virtual memory and multiple threads. The virtual cache directory includes a plurality of directory entries, each entry is associated with a cache line. Each cache line has a corresponding tag. The tag includes a logical address, an address space identifier, a real address bit indicator, and a per thread validity bit for each thread that accesses the cache line. When a subsequent thread determines that the cache line is valid for that thread the validity bit for that thread is set, while not invalidating any validity bits for other threads.

Translation support for a virtual cache

A computer implemented method for saving cache access power is suggested. The cache is provided with a set predictor logic for providing a generated set selection for selecting a set in the cache, and with a set predictor cache for pre-caching generated set indices of the cache. The method comprises further: receiving a part of a requested memory address; checking, in the set predictor cache, whether the requested memory address is already generated; in the case, that the requested memory address has already been generated: securing that the set predictor cache is switched off; issuing the pre-cached generated set index towards the cache; and securing that only that part of the cache is switched on that is associated with the pre-cached generated set index.

Method and arrangement for saving cache power

Disclosed herein is a virtual cache directory in a processor that eliminates address translations when the virtual address and the real address in the cache directory are the same. The processor is configured to support virtual memory and multiple threads. The virtual cache directory includes a plurality of directory entries, each entry is associated with a cache line. Each cache line has a tag. The tag includes a logical address, an address space identifier, a real address bit indicator, and virtual address to real address indicator. This virtual address to real address indicator indicates if the logical address and the real address are the same. When activated, address translation is not performed.

Sharing virtual and real translations in a virtual cache

A method for verification of a design of an electronic circuit is provided. The method includes executing test runs of the design. The method further includes increasing a fail counter if the executing of a test run of the test runs failed. The method further includes increasing a pass counter if the executing of the test run of the test runs passed. The method further includes halting the executing of the test runs of the design if the current ratio of the fail counter versus the pass counter exceeds a predetermined threshold.

System and method for generation of an integrated circuit design

A method and computer processor performs a translation lookaside buffer (TLB) purge with concurrent cache updates. Each cache line contains a virtual address field and a data field. A TLB purge process performs operations for invalidating data in the primary cache memory which do not conform to the current state of the translation lookaside buffer. Whenever the TLB purge process and a cache update process perform a write operation to the primary cache memory concurrently, the write operation by the TLB purge process has no effect on the content of the primary cache memory and the cache update process overwrites a data field in a cache line of the primary cache memory but does not overwrite a virtual address field of said cache line. The translation lookaside buffer purge process is subsequently restored to an earlier state and restarted from the earlier state.

Translation lookaside buffer purging with concurrent cache updates

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Highland, NY, United States of America

Johannes C Reichart