Browse Prior Art Database

Realtime Event Tracing System

IP.com Disclosure Number: IPCOM000082193D
Original Publication Date: 1974-Oct-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 4 page(s) / 59K

Publishing Venue

IBM

Related People

Rose, DB: AUTHOR [+2]

Abstract

Described is a method of tracing events (such as storage address references) which are external to the device being monitored. The method is unique since it is a flexible general purpose tracing method, which provides a high-trace data rate combined with a long uninterrupted trace length. The method described (referred to hereinafter as RAMMAT/CTRACE) is an improvement over the Relocate and Multiprocessor Map and Trace Monitor, RAMMAT, described in the IBM Technical Disclosure Bulletin, Vol. 15, No. 4, September 1972, pages 1377 and 1378. The RAMMAT/CTRACE System consists of three major components: 1) RAMMAT monitor described in the above IBM Technical Disclosure Bulletin publication, modified as shown in Fig. 1 with a continuous CTRAGE function.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 55% of the total text.

Page 1 of 4

Realtime Event Tracing System

Described is a method of tracing events (such as storage address references) which are external to the device being monitored.

The method is unique since it is a flexible general purpose tracing method, which provides a high-trace data rate combined with a long uninterrupted trace length. The method described (referred to hereinafter as RAMMAT/CTRACE) is an improvement over the Relocate and Multiprocessor Map and Trace Monitor, RAMMAT, described in the IBM Technical Disclosure Bulletin, Vol. 15, No. 4, September 1972, pages 1377 and 1378.

The RAMMAT/CTRACE System consists of three major components:
1) RAMMAT monitor described in the above IBM Technical

Disclosure Bulletin publication, modified as shown in Fig.

1 with a continuous CTRAGE function.
2) An IBM System 360 or 370 processor with an attached direct

access storage device (DASD).
3) A standalone IBM System 360 or 370 I/O program resident in

the processor.

Input to the RAMMAT monitor is via the sixteen data probes which have no effect on the monitored device and, therefore, preserve all time dependencies in the traced data. Maximum sustainable trace rates are dependent on the processor and the DASD device used. The CTRACE modification, illustrated in the figure, allows trace records to be sequentially stored in the RAMMAT storage unit by the trace function, while previously stored trace records are being read out by the readout function for transfer to the processor channel. This is accomplished by:
1. Providing a second address generator (ADGEN) to address

storage for the readout function.
2. Providing storage controls to allow access to storage by the

trace function and readout function in an interleaved, as

required manner.
3. Adding logic to detect empty, partially full or full-storage

conditions by comparing storage addresses currently in the

trace ADGEN and readout ADGEN.

The RAMMAT storage is used as a fixed capacity queue, buffering randomly arriving data at a rate determined by the sample rate for the monitored data. The queue service rate is approximately constant and is proportional to the processor channel speed. When the queue capacity is exceeded, the current entries are lost and a lost record entry is made within the trace; thereafter recording continues.

The steps set forth below and in the figure define system operation. Processor I/O Program
1. After initialization, the I/O program issues a start I/G to

the RAMMAT monitor to initiate a read-command chain.

RAMMAT Trace Function
2. The RAMMAT/CTRACE readout function recognizes a read command

as a trace request, and conditions the trace function to

1

Page 2 of 4

begin the trace.
3. A signal on the control probes indicates that the data probes

should be sampled as a trace record.
4. The trace function logic accepts the trace record and requests

storage use from the CTRACE controls.
5. The trace function stores the trace record...