Intel 64 and IA-32 Architectures Software Developers Manual Volume 3B, System Programming Guide Part 2

Table Of Contents
A-30 Vol. 3
PERFORMANCE-MONITORING EVENTS
D2H 01H RAT_STALLS.FLAGS Counts the number of cycles during
which execution stalled due to
several reasons, one of which is a
partial flag register stall. A partial
register stall may occur when two
conditions are met: 1) an instruction
modifies some, but not all, of the
flags in the flag register and 2) the
next instruction, which depends on
flags, depends on flags that were
not modified by this instruction.
D2H 02H RAT_STALLS.REGIST
ERS
This event counts the number of
cycles instruction execution latency
became longer than the defined
latency because the instruction
used a register that was partially
written by previous instruction.
D2H 04H RAT_STALLS.ROB_RE
AD_PORT
Counts the number of cycles when
ROB read port stalls occurred,
which did not allow new micro-ops
to enter the out-of-order pipeline.
Note that, at this stage in the
pipeline, additional stalls may occur
at the same cycle and prevent the
stalled micro-ops from entering the
pipe. In such a case, micro-ops retry
entering the execution pipe in the
next cycle and the ROB-read port
stall is counted again.
D2H 08H RAT_STALLS.SCOREB
OARD
Counts the cycles where we stall
due to microarchitecturally required
serialization. Microcode
scoreboarding stalls.
Table A-2. Non-Architectural Performance Events In the Processor Core for Intel Core
i7 Processors
Event
Num.
Umask
Value
Event Mask
Mnemonic Description Comment