Specifications

April 2012 v1 AMD Opteron™ 6200 Linux Tuning Guide

4.0 Conﬁgure a Performant Production System

This section provides tasks to help you check existing performance and improve future performance on

production systems.

4.1 BIOS Conﬁguration Options

The following are the recommended BIOS conﬁgurations for HPC.

• APM enabled to enable core frequency boost.

• C6 state enabled to allow boost to Pb0 that can provide up to 1 GHz (OPN dependent) core frequency

boost when half of the CUs per die are in halted in C6.

4.2 HPC P-state Mode

Be sure to enable the HPC P-state mode (if available in the BIOS) to prevent APM from decreasing the core

frequency below software P0 frequency (i.e., the base frequency for the CPU, e.g., n GHz for an AMD Opteron™

6276).

4.3 Power Management and Boost

Application Power Management (APM) allows the processor to provide maximum performance while remaining

within the speciﬁed power delivery and removal envelope. APM extends the normal P-states used by the OS

to control core frequency (P0-P6) by adding two boosted P-states, Pb1 and Pb0, of which the OS is unaware.

APM dynamically monitors CPU activity and generates a deterministic approximation of power consumption. If

power consumption exceeds a deﬁned Thermal Design Power (TDP) for the CPU, APM applies a P-state limit to

reduce power consumption. However, if the CPU is using less than TDP, APM will shift to a boosted state (either

Pb1 or Pb0) with an increased core frequency to apply this unused power to improve performance.

APM ensures that average power consumption over a thermally signiﬁcant time period remains at or below the

TDP for the CPU mode being used.

Two levels of boosted P-states are supported. APM can place compute units in the ﬁrst level of boosted Pstates

(Pb1) if the OS kernel requests the highest performance P-state available (e.g., P0) and processor power

consumption remains within the TDP limit. The second level of boosted P-states can only be achieved if

• a subset (usually half) of compute units on each die are halted in CC6,

• software requests P0, the highest performance P-state available, and

• the processor power consumption remains within the TDP limit.

Here is an example of P-states for a Opteron™ 6276 with HPC P-state mode enabled in BIOS.

Pb0 := Freq: 3200 MHz

Pb1 := Freq: 2600 MHz

P0 := Freq: 2300 MHz

P1 := Freq: 2300 MHz

P2 := Freq: 2300 MHz