Nortel DMS-100 Series Maintenance Manual page 117

Enhancements to the real-time subsystem include the following functions:
• To preserve real-time and accomplish reduction of memory blocks. This
function periodically reduces the number of memory blocks available for
external messages. This function reduces associated throttles until the
recovery of some real-time use is complete.
• To define real-time overload as a processor occupancy rate of 75% or
higher for a minimum amount of time. To calculate percentages in the
XLCM is real-time intensive. This is not a flexible method. This method
can result in premature reaction when the XLCM is not in severe real-time
trouble.
• To monitor the amount of time to process certain key maintenance requests
at high levels. These levels must not exceed 100% occupancy. This
threshold makes sure the XLCM responds to these requests before the CM
times out or enters overload. The real-time subsystem benchmarks the
average time to process these key requests. When the time is longer than
this benchmarked average, the subsystem assumes real-time overload.
• To monitor idle task activity and to enter real-time overload. The
subsystem performs this procedure when an idle task does not run for a
specified period of time.
• To characterize the timer task slip counter at a high occupancy rate that
does reach 100%. When the timer task slips at more than the normal high
occupancy rate, the subsystem enters real-time overload.
• To monitor the size of the set message queue. The XLCM is close to
real-time overload when the size reaches 40 or above.
• To include large memory blocks (LMB) in the reduction of memory blocks
component. This function makes sure the recovery of real-time is
completely effective.
XLCM log report appendages
The XLCM appends a new field to the overload messages sent to the CM. This
procedure reflects how extensive the real-time overload is. The CM can be at
CCM04 or later. When this event occurs, this new information appears in the
modified PM180 LCM Enters Overload log and modified PM180 LCM
Overloaded log. The new field contains the following ratio. The ratio of the
maximum real-time distress reached before the overload report must be
generated (values 0-9). This event must occur to the maximum possible level
of real-time distress (values 5-9). A real-time overload indications summary
byte in hexadecimal output is provided as described below.
DMS-100 Family OPM Maintenance Manual ISN07 (TDM)/SN07 (DMS) and up
Functional overview 2-41