VSC7440 datasheet(247/444 Pages) MICROSEMI

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Functional Descriptions

VMDS-10492 VSC7440 Datasheet Revision 4.2

230

Frame copies due to learn-all stack synchronization can be truncated to 64 bytes to save bandwidth on

the line. This is enabled in HSCH::PORT_MODE.TRUNC_ENA.

3.24.9.4 Statistics

The queue system counts frame discards and successful transmissions. Each counted event updates a

counter instance, counting octets in a 40-bit counter and frames in a 32-bit counter. A frame is counted

as discarded when none of the frame’s destination ports are reached, excluding mirror and learn-all

copies. If a frame is discarded, a counter instance, per ingress port, per QoS class per color, is updated.

The color granularity here is only green or yellow, mapped from the analyzed DP value through the

QSYS::DP_MAP settings. A frame transmission is a frame leaving the queue system towards the

rewriter. In this direction, a counter instance per egress port, per QoS class per color, is updated. An

abort counter instance per egress port counts frames discarded due to frame aging, queue system

flushing, or abort requests from the rewriter.

There are statistics available per service counter index, which is provided by the analyzer for ingress

service discard statistics and from the rewriter for egress service transmission statistics. The service

counters are available per counter index, per color.

Access to the statistics is indirect. The QSYS::STAT_CFG configuration register must be set to the port

or service counter index to be accessed, and all counters related to this index can afterwards be read in

the QSYS::CNT registers. The following table lists the available port counters and how they are mapped.

Unused addresses return undefined values. In the expressions, yel = 1 for reading yellow counters and

yel = 0 for green. The mapping from classified DP to color is made in the QSYS::DP_MAP register.

The following table shows the addresses of the frame counters. The equivalent octet counters are found

at the frame counter address plus 64 for the 32 least significant bits and at the frame counter address

plus 128 for the eight most significant bits.

The service counters are reduced in size; 10 bits for the frame part and 18 bits for the octet part.

However, STAT_CFG.STAT_SRV_PKT_ONLY can be set to use all 28 bits for frame counting.

The following table lists the registers associated with statistics access.

Examples:

Table 157 •

Statistics Address Mapping

Statistics Index

Event

0 – 15

Frames received on the port viewed. The first eight counters are for green frames, QoS level 0 –

7. The last eight counters are for yellow frames, defined by the QSYS::DP_MAP register.

16 – 31

Frames dropped on the port viewed. Drops will be for the ingress port point of view or egress,

depending on the DROP_COUNT_EGRESS option. There are eight green counters and eight

yellow counters.

Tail drops on the port views. Drops made by the buffer control.

256 – 271

Transmitted frames on the port viewed. Same layout as for the receive set.

272

Transmit aborted frames for the port viewed. This can be due to aging, flushing, or abortion

decision by the rewriter.

512 + 513

Green and yellow drops for service counter viewed.

768 – 769

Green and yellow transmissions for service counter viewed.

Table 158 •

Statistics Registers Overview

Description

Replication

QSYS::STAT_CFG Selects which counter set index to access. Clears counters.

None

QSYS::CNT

Replicated register with statistics access.

1,024

QSYS::DP_MAP

Maps DP levels to color.

None

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