Released
Datasheet
PM73487 QRT
PMC-Sierra, Inc.
PMC-980618
Issue 3
622 Mbps ATM Traffic Management Device
8.3.1 Receive Service Class (RX SC) Control Block
Base address: 110000h (440000h byte)
Index: 1h
Number of entries: 64 (320 words)
Type: Read/Write
Address =110000 + offset + service_class
h
Table 27. Receive Service Class (RX SC) Control Block Summary
Byte
Offset
Long
Offset
Name
Read or Write
Description
0-FCh
0-3Fh
RX_SC_CONFIG
R/W
The exponents of the maximum and congested queue
depths for this SC.
100-1FCh
40-7Fh RX_SC_STATE
R/W (init only) The current queue depth for this SC.
200-2FCh 80-BFh RX_SC_CUR_CHAN
300-3FCh C0-FFh RX_SC_PREV_CHAN
400-4FCh 100-13Fh RX_SC_CH_COUNT
R/W (init only) The current channel being serviced for this SC.
R/W (init only) The previous channel serviced for this SC.
R/W (init only) The number of channels with cells currently queued.
8.3.1.1 RX_SC_CONFIG
Offset: 0h (0h byte)
Type: Read/Write
Format: Refer to the following table.
Field (Bits)
Description
Not present
(31:16)
RAM is not present in these bit locations.
RX_SC_EXP_MAX_QD
(15:12)
Exponent of the maximum per-SCQ depth. Initialize to the proper setting. Limits the
RX_SC_CUR_QD to:
RX_SC_CUR_QD ≤ 1 + 2RX_SC_EXP_MAX_QD
A value of 0h causes all cells for this SC to be dropped. A value of Fh limits this SC to
31744 cells.
RX_SC_EXP_CONG_QD
(11:8)
Exponent of the congested per-SCQ depth. Initialize to the proper setting. The conges-
tion state is entered when the threshold is exceeded, and the congestion state is exited
when the queue length drops below 50 percent of this threshold. Enables congestion
management when:
RX_SC_CUR_QD > 1 + 2RX_SC_EXP_CONG_QD
A value of 0h causes this SC to be in congestion at all times. A value of 1h may not be
used. A value of Fh causes this SC to enter congestion at a depth of 31744 cells.
Not used
(7:3)
Write with a 0 to maintain software compatibility with future versions.
RX_SC_EXP_WEIGHT
(2:1)
Defines the weight of the SC in the queue service decision algorithm.
weight = 2(RX_SC_EXP_WEIGHT × 2)
This allows weights of 1, 4, 16, or 64.
Not used
(0)
Write with a 0 to maintain software compatibility with future versions.
156
PMC [ PMC-SIERRA, INC ]
