Intel IXP45X Developer's Manual page 930

Intel
• NE watermark – this field indicates the maximum number of occupied entries for
which a queue is considered to be nearly empty. It can be set to 0, 1, 2, 4, 8, 16,
32, or 64 entries.
• NF watermark – this field indicates the maximum number of empty entries for
which a queue is considered to be nearly full. It can be set to 0, 1, 2, 4, 8, 16, 32,
or 64 entries.
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Intel IXP45X and Intel IXP46X Product Line of Network Processors
Developer's Manual
930
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IXP45X and Intel IXP46X Product Line of Network Processors—AHB Queue Manager
• Queue Size(128 words)/Queue Entry Size(4 words) = 32 entries of
4 words each
• Queue Size(128 words)/Queue Entry Size(2 words) = 64 entries of
2 words each
• Queue Size(128 words)/Queue Entry Size(1 word) = 128 entries of
1word each
• Queue Size(32 words)/Queue Entry Size(4 words) = 8 entries of 4
words each
• One more note, when the maximum Q-Manager SRAM utilization is
1984 Words (assuming all queues are being used), the Queue size
cannot be chosen to be the maximum size for every queue. For
example 1984Words/128 words = 15 queues worth of data with 64
words worth of data left over. Note that since one cannot program a
queue size of 15, either the next smallest queue depth will need to
be used or the queues will need to be different depths.
(AQM)
August 2006
Reference Number: 306262-004US