ACPI sleep control

Details ACPI sleep control ACPI sleep control

1998-11-25

2001-07-24

Dharia, Rupal (Department: 2181)

Electrical computers and digital processing systems: support

Computer power control

C713S310000, C713S320000, C713S321000, C713S322000, C713S323000, C713S324000, C713S330000, C713S340000

Reexamination Certificate

active

06266776

ABSTRACT:

BACKGROUND OF THE INVENTION
This application is based on Japanese Patent Application No. 9-329210, filed Nov. 28, 1997, the content of which is incorporated herein by reference.
The present invention relates to a computer system and a system state control method and, more particularly, to a computer system having ON and OFF states and a plurality of sleep states between them as system states, and a system state control method for changing the system state.
Various battery drivable personal computers represented by a notebook type computer have recently been developed. In personal computers of this type, power management techniques have been studied for low power consumption and a short ON state return time. One of these techniques is ACPI (Advanced Configuration and Power Interface) specifications.
The ACPI specifications define ON and OFF states, and in addition a plurality of sleep states between them as system states.
More specifically, the ACPI specifications define system states S
0
through S
5
. S
0
is an ON state (i.e., the system is turned on, and software is in process). S
5
is an OFF state (i.e., execution of all software is complete, and the system is turned off). S
1
through S
4
are intermediate states (called sleep states; i.e., the preceding execution state of software is maintained, but the operation stops).
In S
1
, the contents (contexts) of all the components (e.g., CPU, system memory, and chip sets) of the system, and their power supplies are maintained, and thus the power consumption is maximum of all the sleep states. However, S
1
can immediately return to S
0
. That is, S
0
is the “lightest” sleep state. Note that the light sleep state cannot be maintained for a long time in the battery-driven state of a notebook type personal computer or the like.
S
2
is different from S
1
in that the power supplies of the CPU and the system cache are turned off (and their contents are lost). The necessary power consumption is therefore reduced.
In S
3
, the power supply of only the system memory (and some chip sets) is maintained. That is, the contents of only the system memory (and some chip sets) are maintained. The necessary power supply is much smaller, so that the sleep state can be maintained for a long time in the battery-driven state.
In S
4
, the contents of all the system memory and other components are stored in a non-volatile storage such as a hard disk, and the system power supply is entirely turned off. The power consumption is minimum (equal to S5) of all the sleep states, but it takes the longest time to return to S
0
. That is, S
4
is the “deepest” sleep state.
In return to S
0
from S
2
through S
4
, the lost contents in the system are restored because they are stored before transition to each sleep state. Therefore, upon return to S
0
, software can continuously operate.
The power consumption relationship between the system states, and the relationship of the return time to S
0
are as follows:
Power Consumption: S
0
>S
1
>S
2
>S
3
>S
4
>S
5
Return Time: S
1
<S
2
<S
3
<S
4
<S
5
However, in the current ACPI specifications, no consideration is made to change the depth of the sleep state in accordance with a change in power supply state during sleep. For example, a battery-driven notebook type PC cannot change to such an appropriate sleep state as to minimize the battery consumption. When the battery changes to a low battery state (current sleep state cannot be maintained) in a light sleep state, the sleep state cannot change to a deeper sleep state.
BRIEF SUMMARY OF THE INVENTION
It is an object of the present invention to provide a computer system and system state control method capable of dynamically changing the depth of a sleep state in accordance with a change in power supply state during sleep, and always setting the system state in an optimum sleep state.
To achieve the above object, according to the present invention, there is provided a computer system having ON and OFF states and a plurality of sleep states between the ON and OFF states, comprising means for detecting a change in power supply state of the computer system, and sleep state transition means for, when a change in power supply state is detected while the computer system is in any one of the plurality of sleep states, changing the sleep state of the computer system between the plurality of sleep states in accordance with the change in power supply state.
According to the computer system of the present invention, when a change in power supply state is detected while the computer system is in a sleep state, switching of the sleep state is dynamically changed in accordance with the changed power supply state.
Assume that the user who uses a notebook type PC complying with ACPI specifications (i.e., driven by an AC adapter) in office changes the PC to state S
1
before going home and leaves the office. The last person turns off the circuit breaker of the office and leaves the office. Then, the user's PC maintains state S
1
using its battery. However, the battery may be dead before next morning. The user may use the PC while carrying it. Therefore, the battery power consumption must be minimized. For this purpose, when the system detects the OFF of the external power supply via the AC adapter, the system automatically changes the PC from state S
1
to state S
3
, thereby reducing the battery power consumption. Next morning, when the first person who got office turns on the circuit breaker, the system detects that the external power supply via the AC adapter is turned on again, and returns the PC to state S
1
again. The user can resume use of the PC (in state S
0
) from state S
1
without knowing that the PC is in state S
3
at night. In other words, the system requires a long time to return the PC from S
3
, but allows the user to use the PC within the shortest time without making the user conscious of this.
In this manner, the method of automatically changing the system state between sleep states in accordance with a change in power supply state. Trade-off between shortening of the time interval from a sleep state to system activation, and power saving during sleep can be optimized.
The system state can change between sleep states bidirectionally, i.e., from a light sleep state to a deep sleep state and from a deep sleep state to a light sleep state.
The system state can change not only between two sleep states but also between a plurality of sleep states stepwise in accordance with a change in power supply state.
The sleep state changes more preferably after the lapse of a predetermined time than immediately after a change in power supply is detected. In this case, if the power supply state returns to the original state within the predetermined time, the sleep state does not change.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.


REFERENCES:
patent: 5218607 (1993-06-01), Saito et al.
patent: 5379435 (1995-01-01), Hanaoka
patent: 5471624 (1995-11-01), Enoki et al.
patent: 5511205 (1996-04-01), Kannan et al.
patent: 5623677 (1997-04-01), Townsley et al.
patent: 5710931 (1998-01-01), Nakamura et al.
patent: 5878264 (1999-03-01), Ebrahim
patent: 5999730 (1999-12-01), Lewis
patent: 6105142 (2000-08-01), Goff et al.
patent: 6-175754 (1994-06-01), None
patent: 9-97128 (1997-04-01), None
patent: 9-128106 (1997-05-01), None
Intel/Microsoft/Toshiba, Advanced Configuration and Power Interface Specification Revision 1.0, Dec. 22, 1996, pp. 1-265.

Affiliated with

Also associated with

Rating

ACPI sleep control does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with ACPI sleep control, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and ACPI sleep control will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2555213