C-States; S-States; Power Impact Of Peci Commands Versus C-States - Intel BX80619I73820 Design Manual

7.1.5.4

C-states

The processor PECI client may be fully functional in most core and package C-states.
• The Ping(), GetDIB(), GetTemp(), RdPkgConfig() and WrPkgConfig() commands
have no measurable impact on processor power in any of the core or package C-
states.
• The RdIAMSR() command will complete normally unless the targeted core is in a C-
state that is C3 or deeper. The PECI client will respond with a completion code of
0x82 (see
are C3 or deeper.
• The RdPCIConfigLocal(), WrPCIConfigLocal(), RdPCIConfig() and WrPCIConfig()
commands will not impact the core C-states but may have a measurable impact on
the package C-state. The PECI client will successfully return data without impacting
package C-state if the resources needed to service the command are not in a low
power state.
— If the resources required to service the command are in a low power state, the
PECI client will respond with a completion code of 0x82 (see
definition). If this is the case, setting the "Wake on PECI" mode bit as described
in
successful completion of the command. The exact power impact of a pop-up to
C2 will vary by product SKU, the C-state from which the pop-up is initiated and
the negotiated PECI bit rate.
Table 7-19. Power Impact of PECI Commands versus C-states
Command
Ping()
GetDIB()
GetTemp()
RdPkgConfig()
WrPkgConfig()
RdIAMSR()
RdPCIConfigLocal()
WrPCIConfigLocal()
RdPCIConfig()
WrPCIConfig()
7.1.5.5

S-states

The processor PECI client is always guaranteed to be operational in the S0 sleep state.
• The Ping(), GetDIB(), GetTemp(), RdPkgConfig(), WrPkgConfig(),
RdPCIConfigLocal() and WrPCIConfigLocal() will be fully operational in S0 and S1.
Responses in S3 or deeper states are dependent on POWERGOOD assertion status.
• The RdPCIConfig(), WrPCIConfig() and RdIAMSR() responses are guaranteed in S0
only. Behavior in S1 or deeper states is indeterminate.
• PECI behavior is indeterminate in the S3, S4 and S5 states and responses to PECI
originator requests when the PECI client is in these states cannot be guaranteed.
90
Table 7-23 for definition) for RdIAMSR() accesses in core C-states that
Section 7.1.2.6 can cause a package 'pop-up' to the C2 state and enable
Not measurable
Not measurable
Not measurable
Not measurable
Not measurable
Not measurable. PECI client will not return valid data in core C-state that is C3 or
deeper
May require package 'pop-up' to C2 state
May require package 'pop-up' to C2 state
May require package 'pop-up' to C2 state
May require package 'pop-up' to C2 state
Table 7-23
Power Impact
Thermal/Mechanical Specifications and Design Guide
PECI Interface
for