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1995-01-13
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OSOTPERF - OS/2 2.XX Performance considerations.
10/04/94
================================================================
OS/2 2.XX Performance considerations.
================================================================
Please Read Entire Document for Full Explanation of Procedures
---------------------------------------------------------------
Most performance problems are hardware related
HARDWARE
---------
To determine if you have a hardware problem, start your system
with a plain copy of your CONFIG.SYS without any applicaitons
running. If the performance is not good, you may have a
hardware problem.
Memory
------
The memory your system uses can affect Performance can actually
degrade if you add a memory expansion card to a Non Micro-Channel
system. To access memory on the expansion card, the signals have
to go through the bus which, in most cases, run slower than
memory accessed from SIMMS.
Performance problems on ISA systems after installing extra memory
-----------------------------------------------------------------
On several ISA systems, performance problems appear when
additional memory is installed on the system. The most common
cause is relates to external processor chache memory, which is
referred to as level two or secondary cache memory. The issues
with these cache memories are:
1. System board/BIOS does not support caching memory above 16M
(or 64M in some cases). You need to upgrade either the system
board or the BIOS; whichever is the limiting factor.
2. System board/BIOS does not support caching memory above 16M
(or 64M in some cases) without installing additional cache
memory.
3. BIOS parameter must be updated to cache memory above 16M.
This appears in some systems with AMI BIOS but is not
necessarily limited to that BIOS.
4. The cache was disabled when system setup updated the BIOS with
the new amount of installed memory.
Less common reasons for upgrading memory causing
performance problems are:
1. The new memory is on an expansion card that is limited to the
speed of the system bus (8MHz on ISA systems) instead of on the
planer (system board) where the limitation does not exist.
2. Slower memory was added to the system.
Additional BIOS paramters to check
----------------------------------
On some systems there is a BIOS parameter for system speed.
Ensure this is set to the fastest option. The "Wait States"
parameter in the BIOS Setup program was changed from the optimal
values and needs to be decreased.
Cache
-----
Internal and external cache should always be enabled except
during the installation of OS/2. If you experience a problem
with your cache enabled, for example, Traps, etc., the external
cache probably needs to be replaced.
================================================================
SOFTWARE
-----------------------------------------------------------------
If your system performs as expected when running only OS/2, then
you probably have a software problem.
Device Drivers
--------------
Some device drivers can generate excessive interrupt calls that
slow down your system. To find the problem, start with a plain
CONFIG.SYS and add a device driver one at a time. When the
system's performance degrades, the last device driver you added
is most likely the cause. Some device drivers might also need to
be upgraded. Contact the vendor of the device driver for
assistance.
Desktop
-------
You can increase performance by disabling the animation in the
dessktop settings.
CHKDSK
------
Running CHKDSK can resolve problems on your hard disk that cause
performance problems.
Applications
------------
Some applications require a lot of resources to run. The
application vendor may know how to make their product run
faster. Adding more memory to your system may also help.
For DOS and windows performance problems see the
performance information for DOS applications.
CONFIG.SYS
----------
SET RESTARTOBJECTS=NO - With this statement in the
CONFIG.SYS, the system starts without running any applications
except what is in your startup.cmd file.
Diskcache - (FAT only) Changing the value in this field,
increases or decreases performance. The specified value
depends on the amount of available ram.
IFS - (HPFS only) The /CACHE:<value> determines the amount of
software cache available to the HPFS installed partitions.
Priority disk I/O - specifies the disk I/O priority for
applications running in the foreground. ON gives foreground
applications more CPU time.
MAXWAIT - By decreasing this value, a regular or server process
has its priority increased at a faster rate.
TimeSlice - Changing these settings gives the system more/less
time to a process of equal priority.
Threads - sets the maximum number of independent actions
(threads) for the system.
Note: See on-line help for additional information.
Utilities
---------
OS20MEMU.zip - is an unsupported utility, available from
the IBM PCC BSS (919-0517-0001), that lets you to view
memory consumption.
SPM/2 - System performance monitor/2. This application is
available from the order center. (800-3IBM-OS2). This
application is for sale separately of OS/2 and is supported.