Front End Bandwidth Limited Due To Supply Out Of The Legacy Decode Pipeline

Front End Bandwidth Limited Due To Supply Out Of The Legacy Decode Pipeline

TITLE: Front End Bandwidth Limited Due To Supply Out Of The Legacy Decode Pipeline

ISSUE_NAME: Frontend^FE_bandwidth^MITE

DESCRIPTION:

Cycles the front end was bound on bandwidth supply out of MITE, which is the legacy decode pipeline

RELEVANCE:

When the front end cannot deliver enough uops when the back end is requesting uops, this can potentially indicate a front end limitation which is affecting performance.  With this metric, the limited bandwidth is due to limitations in the legacy decode pipeline being unable to supply 4 uops in a particular cycle.  Recommendation is to look into the other legacy decode pipeline related metrics to root cause the issue.

EXAMPLE:

Excessive resteers (from instructions which are decoded into two to four micro-ops) would be an example of how the front end bandwith may be limited in the legacy decode pipeline.

SOLUTION:

RELATED_SOURCES:

NOTES:

EQUATION:  (IDQ.ALL_MITE_CYCLES_ANY_UOPS-IDQ.ALL_MITE_CYCLES_4_UOPS) / CPU_CLK_UNHALTED.THREAD

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