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Dear experts,
I have a question regarding the "Retire Stalls" hardware-event metric. Hereit says:
This metric is defined as a ratio of the number of cycles when no micro-operations are retired to all cycles. In the absence of performance issues, long latency operations, and dependency chains, retire stalls are insignificant. Otherwise, retire stalls result in a performance penalty. On Intel microarchitecture codename Nehalem, this metric is based on precise events that do not suffer from significant skid.
From the definition, I would think the ratio should always be less than 1. However, in my Amplifier XE run, I see this number can be as large as 39 in my application.
Could someone shed some light on this number? Thanks a lot!
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Sorry that I don't know what predefined analysis type you use, or you created a newanalysis type for PMU event-based sampling collection? If so, I think that event RESOURCE_STALLS.ROB_FULL should be used.
This event counts the number of cycles when the number of instructions in the pipeline waiting for retirement reaches the limit the processor (Re-oder Buffer (ROB) is full) can handle. This is a penalty (with cycles) from Resource Stall.
Please describeyour problem in detail, ifpossible. Thank you!
Regards, Peter
This event counts the number of cycles when the number of instructions in the pipeline waiting for retirement reaches the limit the processor (Re-oder Buffer (ROB) is full) can handle. This is a penalty (with cycles) from Resource Stall.
Please describeyour problem in detail, ifpossible. Thank you!
Regards, Peter

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