Subsystems Power Management; Ultrasparc Iii Processor(S), Main Memory, And Sun Crossbar Interconnect; Epci Bus; Storage Devices - Sun Microsystems Sun Blade 1000 Service Manual

C.6.1

Subsystems Power Management

Power management of each subsystem is controlled by the Power Management
software and is configured through a graphical user interface (GUI). The idle time
before a subsystem is power managed can be adjusted by the user. Subsystems may
also be left at full power (infinite idle time) or forced into low-power mode (zero idle
time).
The following are brief descriptions of the subsystems' power management
behavior. Refer to the following sections for more details on each subsystem.
C.6.1.1 UltraSPARC III Processor(s), Main Memory, and Sun CrossBar
Interconnect
This subsystem corresponds to the core of the Sun Blade 1000 and Sun Blade 2000
workstation and represents most of the workstation power budget. Power is saved
in this subsystem by lowering the system clock frequency. The Power Management
software manages the frequency shifts by monitoring idle and active time as
reported by the Solaris operating environment. When idle time, determined by what
code is being executed, reaches a certain level by software, the system clock is
transitioned to a lower frequency. This is done in two steps:
1. First, the clock is cut to 1/2, then to 1/32 of the nominal frequency.
2. When CPU activity increases and the idle time decreases to a certain level, the
frequency is shifted back to 1/2 then to full speed.
The external cache also supports a sleep mode that is automatically activated when
the system frequency is reduced and no access is active.
C.6.1.2

EPCI Bus

Devices that support the PCI Bus Power Management Interface Specification are put
into sleep mode. If no device has the ability to request service through an
interrupt or similar signal, the clock may be completely turned off to save more
power.
C.6.1.3

Storage Devices

FC-AL (hard drives), SCSI CD-ROM, and DVD-ROM devices spin down when
inactive.
C-52 Sun Blade 1000 and Sun Blade 2000 Service Manual • January 2002