Abstract: Systems, apparatuses, and methods for generating a measurement of write memory bandwidth are disclosed. A control unit monitors writes to a cache hierarchy. If a write to a cache line is a first time that the cache line is being modified since entering the cache hierarchy, then the control unit increments a write memory bandwidth counter. Otherwise, if the write is to a cache line that has already been modified since entering the cache hierarchy, then the write memory bandwidth counter is not incremented. The first write to a cache line is a proxy for write memory bandwidth since this will eventually cause a write to memory. The control unit uses the value of the write memory bandwidth counter to generate a measurement of the write memory bandwidth. Also, the control unit can maintain multiple counters for different thread classes to calculate the write memory bandwidth per thread class.

Abstract: Systems, apparatuses, and methods for dynamically adjusting cache policies to reduce execution core wait time are disclosed. A processor includes a cache subsystem. The cache subsystem includes one or more cache levels and one or more cache controllers. A cache controller partitions a cache level into two test portions and a remainder portion. The cache controller applies a first policy to the first test portion and applies a second policy to the second test portion. The cache controller determines the amount of time the execution core spends waiting on accesses to the first and second test portions. If the measured wait time is less for the first test portion than for the second test portion, then the cache controller applies the first policy to the remainder portion. Otherwise, the cache controller applies the second policy to the remainder portion.

Abstract: Systems, apparatuses, and methods for routing interrupts on a coherency probe network are disclosed. A computing system includes a plurality of processing nodes, a coherency probe network, and one or more control units. The coherency probe network carries coherency probe messages between coherent agents. Interrupts that are detected by a control unit are converted into messages that are compatible with coherency probe messages and then routed to a target destination via the coherency probe network. Interrupts are generated with a first encoding while coherency probe messages have a second encoding. Cache subsystems determine whether a message received via the coherency probe network is an interrupt message or a coherency probe message based on an encoding embedded in the received message. Interrupt messages are routed to interrupt controller(s) while coherency probe messages are processed in accordance with a coherence probe action field embedded in the message.

Abstract: Systems, apparatuses, and methods for arbitrating threads in a computing system are disclosed. A computing system includes a processor with multiple cores, each capable of simultaneously processing instructions of multiple threads. When a thread throttling unit receives an indication that a shared cache has resource contention, the throttling unit sets a threshold number of cache misses for the cache. If the number of cache misses exceeds this threshold, then the throttling unit notifies a particular upstream computation unit to throttle the processing of instructions for the thread. After a time period elapses, if the cache continues to exceed the threshold, then the throttling unit notifies the upstream computation unit to more restrictively throttle the thread by performing one or more of reducing the selection rate and increasing the time period. Otherwise, the unit notifies the upstream computation unit to less restrictively throttle the thread.

Abstract: Systems, apparatuses, and methods for employing system probe filter aware last level cache insertion bypassing policies are disclosed. A system includes a plurality of processing nodes, a probe filter, and a shared cache. The probe filter monitors a rate of recall probes that are generated, and if the rate is greater than a first threshold, then the system initiates a cache partitioning and monitoring phase for the shared cache. Accordingly, the cache is partitioned into two portions. If the hit rate of a first portion is greater than a second threshold, then a second portion will have a non-bypass insertion policy since the cache is relatively useful in this scenario. However, if the hit rate of the first portion is less than or equal to the second threshold, then the second portion will have a bypass insertion policy since the cache is less useful in this case.

Abstract: Systems, apparatuses, and methods for routing interrupts on a coherency probe network are disclosed. A computing system includes a plurality of processing nodes, a coherency probe network, and one or more control units. The coherency probe network carries coherency probe messages between coherent agents. Interrupts that are detected by a control unit are converted into messages that are compatible with coherency probe messages and then routed to a target destination via the coherency probe network. Interrupts are generated with a first encoding while coherency probe messages have a second encoding. Cache subsystems determine whether a message received via the coherency probe network is an interrupt message or a coherency probe message based on an encoding embedded in the received message. Interrupt messages are routed to interrupt controller(s) while coherency probe messages are processed in accordance with a coherence probe action field embedded in the message.

Abstract: Systems, apparatuses, and methods for generating a measurement of write memory bandwidth are disclosed. A control unit monitors writes to a cache hierarchy. If a write to a cache line is a first time that the cache line is being modified since entering the cache hierarchy, then the control unit increments a write memory bandwidth counter. Otherwise, if the write is to a cache line that has already been modified since entering the cache hierarchy, then the write memory bandwidth counter is not incremented. The first write to a cache line is a proxy for write memory bandwidth since this will eventually cause a write to memory. The control unit uses the value of the write memory bandwidth counter to generate a measurement of the write memory bandwidth. Also, the control unit can maintain multiple counters for different thread classes to calculate the write memory bandwidth per thread class.

Abstract: Systems, apparatuses, and methods for arbitrating threads in a computing system are disclosed. A computing system includes a processor with multiple cores, each capable of simultaneously processing instructions of multiple threads. When a thread throttling unit receives an indication that a shared cache has resource contention, the throttling unit sets a threshold number of cache misses for the cache. If the number of cache misses exceeds this threshold, then the throttling unit notifies a particular upstream computation unit to throttle the processing of instructions for the thread. After a time period elapses, if the cache continues to exceed the threshold, then the throttling unit notifies the upstream computation unit to more restrictively throttle the thread by performing one or more of reducing the selection rate and increasing the time period. Otherwise, the unit notifies the upstream computation unit to less restrictively throttle the thread.

Abstract: Systems, apparatuses, and methods for employing system probe filter aware last level cache insertion bypassing policies are disclosed. A system includes a plurality of processing nodes, a probe filter, and a shared cache. The probe filter monitors a rate of recall probes that are generated, and if the rate is greater than a first threshold, then the system initiates a cache partitioning and monitoring phase for the shared cache. Accordingly, the cache is partitioned into two portions. If the hit rate of a first portion is greater than a second threshold, then a second portion will have a non-bypass insertion policy since the cache is relatively useful in this scenario. However, if the hit rate of the first portion is less than or equal to the second threshold, then the second portion will have a bypass insertion policy since the cache is less useful in this case.

Abstract: Systems, apparatuses, and methods for generating a measurement of write memory bandwidth are disclosed. A control unit monitors writes to a cache hierarchy. If a write to a cache line is a first time that the cache line is being modified since entering the cache hierarchy, then the control unit increments a write memory bandwidth counter. Otherwise, if the write is to a cache line that has already been modified since entering the cache hierarchy, then the write memory bandwidth counter is not incremented. The first write to a cache line is a proxy for write memory bandwidth since this will eventually cause a write to memory. The control unit uses the value of the write memory bandwidth counter to generate a measurement of the write memory bandwidth. Also, the control unit can maintain multiple counters for different thread classes to calculate the write memory bandwidth per thread class.

Abstract: A cache stores, along with data that is being transferred from a higher level cache to a lower level cache, information indicating the higher level cache location from which the data was transferred. Upon receiving a request for data that is stored at the location in the higher level cache, a cache controller stores the higher level cache location information in a status tag of the data. The cache controller then transfers the data with the status tag indicating the higher level cache location to a lower level cache. When the data is subsequently updated or evicted from the lower level cache, the cache controller reads the status tag location information and transfers the data back to the location in the higher level cache from which it was originally transferred.

Abstract: Systems, apparatuses, and methods for arbitrating threads in a computing system are disclosed. A computing system includes a processor with multiple cores, each capable of simultaneously processing instructions of multiple threads. When a thread throttling unit receives an indication that a shared cache has resource contention, the throttling unit sets a threshold number of cache misses for the cache. If the number of cache misses exceeds this threshold, then the throttling unit notifies a particular upstream computation unit to throttle the processing of instructions for the thread. After a time period elapses, if the cache continues to exceed the threshold, then the throttling unit notifies the upstream computation unit to more restrictively throttle the thread by performing one or more of reducing the selection rate and increasing the time period. Otherwise, the unit notifies the upstream computation unit to less restrictively throttle the thread.

Abstract: Systems, apparatuses, and methods for employing system probe filter aware last level cache insertion bypassing policies are disclosed. A system includes a plurality of processing nodes, a probe filter, and a shared cache. The probe filter monitors a rate of recall probes that are generated, and if the rate is greater than a first threshold, then the system initiates a cache partitioning and monitoring phase for the shared cache. Accordingly, the cache is partitioned into two portions. If the hit rate of a first portion is greater than a second threshold, then a second portion will have a non-bypass insertion policy since the cache is relatively useful in this scenario. However, if the hit rate of the first portion is less than or equal to the second threshold, then the second portion will have a bypass insertion policy since the cache is less useful in this case.

Abstract: A cache stores, along with data that is being transferred from a higher level cache to a lower level cache, information indicating the higher level cache location from which the data was transferred. Upon receiving a request for data that is stored at the location in the higher level cache, a cache controller stores the higher level cache location information in a status tag of the data. The cache controller then transfers the data with the status tag indicating the higher level cache location to a lower level cache. When the data is subsequently updated or evicted from the lower level cache, the cache controller reads the status tag location information and transfers the data back to the location in the higher level cache from which it was originally transferred.

Abstract: Systems, apparatuses, and methods for dynamically adjusting cache policies to reduce execution core wait time are disclosed. A processor includes a cache subsystem. The cache subsystem includes one or more cache levels and one or more cache controllers. A cache controller partitions a cache level into two test portions and a remainder portion. The cache controller applies a first policy to the first test portion and applies a second policy to the second test portion. The cache controller determines the amount of time the execution core spends waiting on accesses to the first and second test portions. If the measured wait time is less for the first test portion than for the second test portion, then the cache controller applies the first policy to the remainder portion. Otherwise, the cache controller applies the second policy to the remainder portion.

Abstract: Systems, apparatuses, and methods for generating a measurement of write memory bandwidth are disclosed. A control unit monitors writes to a cache hierarchy. If a write to a cache line is a first time that the cache line is being modified since entering the cache hierarchy, then the control unit increments a write memory bandwidth counter. Otherwise, if the write is to a cache line that has already been modified since entering the cache hierarchy, then the write memory bandwidth counter is not incremented. The first write to a cache line is a proxy for write memory bandwidth since this will eventually cause a write to memory. The control unit uses the value of the write memory bandwidth counter to generate a measurement of the write memory bandwidth. Also, the control unit can maintain multiple counters for different thread classes to calculate the write memory bandwidth per thread class.

Abstract: A processing system indicates the pendency of a memory access request for data at the cache entry that is assigned to store the data in response to the memory access request. While executing instructions, the processor issues requests for data to the cache most proximal to the processor. In response to a cache miss, the cache controller identifies an entry of the cache to store the data in response to the memory access request, and stores an indication that the memory access request is pending at the identified cache entry. If the cache controller receives a subsequent memory access request for the data while the memory access request is pending at the higher level of the memory hierarchy, the cache controller identifies that the memory access request is pending based on the indicator stored at the entry.

Abstract: Systems, apparatuses, and methods for routing interrupts on a coherency probe network are disclosed. A computing system includes a plurality of processing nodes, a coherency probe network, and one or more control units. The coherency probe network carries coherency probe messages between coherent agents. Interrupts that are detected by a control unit are converted into messages that are compatible with coherency probe messages and then routed to a target destination via the coherency probe network. Interrupts are generated with a first encoding while coherency probe messages have a second encoding. Cache subsystems determine whether a message received via the coherency probe network is an interrupt message or a coherency probe message based on an encoding embedded in the received message. Interrupt messages are routed to interrupt controller(s) while coherency probe messages are processed in accordance with a coherence probe action field embedded in the message.

Abstract: A processing system includes a cache that includes a cache lines that are partitioned into a first subset of the cache lines and a second subsets of the cache lines. The processing system also includes one or more counters that are associated with the second subsets of the cache lines. The processing system further includes a processor configured to modify the one or more counters in response to a cache hit or a cache miss associated with the second subsets. The one or more counters are modified by an amount determined by one or more characteristics of a memory access request that generated the cache hit or the cache miss.

Abstract: A processor includes an operations scheduler to schedule execution of operations at, for example, a set of execution units or a cache of the processor. The operations scheduler periodically adds sets of operations to a tracking array, and further identifies when an operation in the tracked set is blocked from execution scheduling in response to, for example, identifying that the operation is dependent on another operation that has not completed execution. The processor further includes a counter that is adjusted each time an operation in the tracking array is blocked from execution, and is reset each time an operation in the tracking array is executed. When the value of the counter exceeds a threshold, the operations scheduler prioritizes the remaining tracked operations for execution scheduling.