Browse Prior Art Database

Automatic Data Compression Control for Hibernation

IP.com Disclosure Number: IPCOM000117627D
Original Publication Date: 1996-Apr-01
Included in the Prior Art Database: 2005-Mar-31
Document File: 2 page(s) / 76K

Publishing Venue

IBM

Related People

Aihara, T: AUTHOR [+3]

Abstract

Disclosed is a method for optimizing the performance of hibernation of Personal Computers (PCs), when data compression is introduced in power management technology. Hibernation is an operation mode in which almost all of the circuits are powered down after system memory data, video data, and hardware context information are saved in hard disk. Wake-up is an operation for resuming from hibernation mode. During the course of waking-up, the data saved in the hard disk before entering hibernation are restored to the respective places. Also, the hibernation/ wake-up function also can be used as an 'instant on/off' feature, because the time required for waking-up is generally shorter than the normal operating system boot up time.

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Automatic Data Compression Control for Hibernation

      Disclosed is a method for optimizing the performance of
hibernation of Personal Computers (PCs), when data compression is
introduced in power management technology.  Hibernation is an
operation mode in which almost all of the circuits are powered down
after system memory data, video data, and hardware context
information are saved in hard disk.  Wake-up is an operation for
resuming from hibernation mode.  During the course of waking-up, the
data saved in the hard disk before entering hibernation are restored
to the respective places.  Also, the hibernation/ wake-up function
also can be used as an 'instant on/off' feature, because the time
required for waking-up is generally shorter than the normal operating
system boot up time.  In order to improve the performance of
hibernation, the time required for the data transfer to the hard disk
must be reduced.

      If software data compression is adopted for the data transfer
during the course of the hibernation, then the performance is
degraded because of the compression overhead.  However, if you
carefully design  the compression algorithm, performance improvement
can be obtained by setting the compression ratio being high.  The
compression ratio depends  on the usage of the system memory, in
other words the types of operating  system and application program.
Consequently, sometimes even the well-designed data compression
results in longer hibernation and wake-up  time.

      The disclosed solution realizes optimized hibernation
performance by automatically disabling data compression by evaluating
the compression ratio of the system memory.

      To improve the performance of hibernation/wake-up by software
data compression, a very simple and fast algorithm must be adopted.
With this approach, better performance can be obtained in most of the
cases when the system memory size is large.  However, when the system
memory size is smaller and the software fills the memory with random
data, the compression ratio becomes significantly low depending on
the data patterns used by the software.  If a user regardlessly keeps
on using hibernation/wake-up cycles without any normal
shutdown/reboot operation, the compression ratio may also become low
so that the hibernation perfor...