TDC: Data errors in INET (internet) record

[clarklk]

There are problems with the data reported by TDC within both the "TCP" and the "ICMP" parts of the INET data record. These problems affect all current and previous releases of TDC V2.x and TDC_RT V2.x.

TDC_INET data records: "TCP" data
---------------------------------

The "TCP" data problem described here will be dealt with in a future release, which will also correct previously-collected data records as they are read.

A data item, TDC_INET_TCP_RCVDUPBYTE, SHOULD have been represented in the INET record, between TDC_INET_TCP_RCVDUPPACK and TDC_INET_TCP_RCVPARTDUPPACK; that data item was omitted from the record definition.

For now, the following TDC_INET_TCP_* data items can be interpreted as described below.

The effect of the data item omission is that:

1) The value reported for TDC_INET_TCP_RCVPARTDUPPACK is actually the value that would have been reported for the missing TDC_INET_TCP_RCVDUPBYTE;

2) The value reported for TDC_INET_TCP_RCVPARTDUPBYTE is actually the value that should have been reported for TDC_INET_TCP_RCVPARTDUPPACK;

3) The value reported for TDC_INET_TCP_RCVOOPACK is actually the value that should have been reported for TDC_INET_TCP_RCVPARTDUPBYTE;

4) And, in general, for the following list of data items, the correct value is the value reported for the immediately following data item in the TDC INET record (and in the list below):

TDC_INET_TDC_RCVPARTDUPPACK
TDC_INET_TCP_RCVPARTDUPBYTE
TDC_INET_TCP_RCVOOPACK
TDC_INET_TCP_RCVOOBYTE
TDC_INET_TCP_RCVPACKAFTERWIN
TDC_INET_TCP_RCVBYTEAFTERWIN
TDC_INET_TCP_RCVAFTERCLOSE
TDC_INET_TCP_RCVWINPROBE
TDC_INET_TCP_RCVDUPACK
TDC_INET_TCP_RCVACKTOOMUCH
TDC_INET_TCP_RCVACKPACK
TDC_INET_TCP_RCVACKBYTE
TDC_INET_TCP_RCVWINUPD
TDC_INET_TCP_NOOUTPUTBUFFS
TDC_INET_TCP_SKIPCHECKSUM
TDC_INET_TCP_PENDINGCONNECTIONDROPPED
TDC_INET_TCP_IGNORED_TSOPT
TDC_INET_TCP_PROCESSING_TSOPT
TDC_INET_TCP_RECYCLED_TPS

Note that a correct value for TDC_INET_TCP_RECYCLED_TPS cannot be recovered.


TDC_INET data records: "ICMP" data
---------------------------------

Only the first 3 of the 8 "ICMP" data items provide valid values: TDC_INET_ICMP_ERROR, TDC_INET_ICMP_OLDSHORT, and TDC_INET_ICMP_OLDICMP.

A "going-forward" fix for the "ICMP" data will also be provided in a future release. That fix will not be able to recover values for the other 5 "ICMP" data items from previously-collected data records when reading files.

Lee Clark
OpenVMS Engineering

[Wim Van den Wyngaert]

Stupid question : where is the T of TDC standing for (yes I know Perf Data Coll) ?

Wim

[Sebastian Bazley]

"The" - I think.