COHERENT PROXY FOR ATTACHED PROCESSOR
First Claim
1. A method of data processing, comprising:
- receiving a memory access request from an attached processor (AP) at a coherent attached processor proxy (CAPP) of a primary coherent system, wherein the CAPP includes a CAPP directory of contents of a cache memory in the AP that holds copies of memory blocks belonging to a coherent address space of the primary coherent system, and wherein the receiving includes receiving an expected coherence state of a target address of the memory access request with respect to the cache memory of the AP;
in response to receiving the memory access request at the CAPP, the CAPP determining a coherence state of the target address with respect to the CAPP and determining whether or not the expected state matches the coherence state determined by the CAPP;
in response to determining that the expected state matches the coherence state determined by the CAPP, the CAPP issuing a memory access request corresponding to that received from the AP on a system fabric of the primary coherent system; and
in response to determining that the expected state does not match the coherence state determined by the CAPP, the CAPP transmitting a failure message to the AP without issuing on the system fabric a memory access request corresponding to that received from the AP.
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Accused Products
Abstract
A coherent attached processor proxy (CAPP) of a primary coherent system receives a memory access request from an attached processor (AP) and an expected coherence state of a target address of the memory access request with respect to a cache memory of the AP. In response, the CAPP determines a coherence state of the target address and whether or not the expected state matches the determined coherence state. In response to determining that the expected state matches the determined coherence state, the CAPP issues a memory access request corresponding to that received from the AP on a system fabric of the primary coherent system. In response to determining that the expected state does not match the coherence state determined by the CAPP, the CAPP transmits a failure message to the AP without issuing on the system fabric a memory access request corresponding to that received from the AP.
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Citations
8 Claims
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1. A method of data processing, comprising:
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receiving a memory access request from an attached processor (AP) at a coherent attached processor proxy (CAPP) of a primary coherent system, wherein the CAPP includes a CAPP directory of contents of a cache memory in the AP that holds copies of memory blocks belonging to a coherent address space of the primary coherent system, and wherein the receiving includes receiving an expected coherence state of a target address of the memory access request with respect to the cache memory of the AP; in response to receiving the memory access request at the CAPP, the CAPP determining a coherence state of the target address with respect to the CAPP and determining whether or not the expected state matches the coherence state determined by the CAPP; in response to determining that the expected state matches the coherence state determined by the CAPP, the CAPP issuing a memory access request corresponding to that received from the AP on a system fabric of the primary coherent system; and in response to determining that the expected state does not match the coherence state determined by the CAPP, the CAPP transmitting a failure message to the AP without issuing on the system fabric a memory access request corresponding to that received from the AP. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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Specification