Intel® Xeon® Processor E5-2600 Product Family Uncore Performance Monitoring
30 Reference Number: 327043-001
2.3.4 CBo Performance Monitoring Events
2.3.4.1 An Overview:
The performance monitoring events within the CBo include all events internal to the LLC as well as
events which track ring related activity at the CBo/Core ring stops.
CBo performance monitoring events can be used to track LLC access rates, LLC hit/miss rates, LLC
eviction and fill rates, and to detect evidence of back pressure on the LLC pipelines. In addition, the
CBo has performance monitoring events for tracking MESI state transitions that occur as a result of
data sharing across sockets in a multi-socket system. And finally, there are events in the CBo for
tracking ring traffic at the CBo/Core sink inject points.
Every event in the CBo is from the point of view of the LLC and is not associated with any specific core
since all cores in the socket send their LLC transactions to all CBos in the socket. However, the PMON
logic in the CBo provides a thread-id field in the Cn_MSR_PMON_BOX_FILTER register which can be
applied to the CBo events to obtain the interactions between specific cores and threads.
There are separate sets of counters for each CBo instance. For any event, to get an aggregate count
of that event for the entire LLC, the counts across the CBo instances must be added together. The
counts can be averaged across the CBo instances to get a view of the typical count of an event from
the perspective of the individual CBos. Individual per-CBo deviations from the average can be used to
identify hot-spotting across the CBos or other evidences of non-uniformity in LLC behavior across the
CBos. Such hot-spotting should be rare, though a repetitive polling on a fixed physical address is one
obvious example of a case where an analysis of the deviations across the CBos would indicate hot-
spotting.
2.3.4.2 Acronyms frequently used in CBo Events:
The Rings:
AD (Address) Ring - Core Read/Write Requests and Intel QPI Snoops. Carries Intel QPI requests and
snoop responses from C to Intel® QPI.
BL (Block or Data) Ring - Data == 2 transfers for 1 cache line
0x194 PCIWiLF PCIe Write (non-allocating)
0x195 PCIPRd PCIe UC Read
0x19C PCIItoM PCIe Write (allocating)
0x19E PCIRdCur PCIe read current
0x1C4 WbMtoI Request writeback Modified invalidate line
0x1C5 WbMtoE Request writeback Modified set to Exclusive
0x1C8 ItoM Request Invalidate Line
0x1E4 PCINSRd PCIe Non-Snoop Read
0x1E5 PCINSWr PCIe Non-Snoop Write (partial)
0x1E6 PCINSWrF PCIe Non-Snoop Read (full)
Table 2-13. Opcode Match by IDI Packet Type for Cn_MSR_PMON_BOX_FILTER.opc (Sheet
2 of 2)
opc
Value
Opcode Defn
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