GAF 4957977 Last Part

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The processing time at the Packet Processing Uint is important to complete processing packets

on a budget time within a period of the 100 Gbps.

Single segment message packets, which the carry a single data application between the two ends,

required to be processed at the PPU. When the SSM is identified, it can be sent ‘as is’ to its

destination buffer. There is no linked-list processing required at the receiving side or generation

of a header at the sending side. The RISC processes the 1500 packet within 32 ns, whereas total

budget time required for 100 Gbps is 123 ns, this is makes the core able to process the next packet or to

read the FIFO 3. The 512 bytes packets are also processed on time, 34.5 ns. Hover, when the packets get

smaller than the 512 bytes the processing cap time in become critical. This is due to the RISC processes

21 cycles (including four idle cycles) to complete process the 256 packets. The processing time get larger

when the packet gets smaller. Even though, with small packets there are a processing delay time, the

core capable to complete processing the large packets within a short time than the one required for 100

Gbps. 1500 bytes packets processed in 32 ns, saving 91 ns.

More MHz of the clock rate are required if the MUT is less than 512 bytes. This is because the

PPU is expected to send and receive more packets in a second..

The other small packets that the NI could receive, are TCP signaling packets. This type of

packets travel between the large packets to the destination, the Core at the end has to process

these small packets or send the signaling packets to another destination. Next section illustrates

the small packet processing at the NI, when the RISC core clock rate is 750 MHz and the DMA

is 3759 MHz.

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. The processing time of the TCP packets at the PPU when the receiver RISC is 752 MHz and the

DMA is 3759 MHz, are presented in the Table 6.5. A larger packet, which includes large

payload, increases the available processing time. The RISC core able to complete the large

packet such as 1500 bytes, 1024 bytes and 512 bytes within a short time, within the budget time .

the 1500 bytes packets processed within 33.3 ns, where as the budget time is 123 ns. the reming

time is 89.7 ns. the RISC capable he 1500 bytes a budget time. Minimum size packets, such as

64 bytes, need 7 ns, whereas the large packet, the 1500 bytes, needs about 123 ns per packet. The

SSM which carry single data large packet RISC processors required to complete packets within a

budget time.

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- Please Note --- the you Yellow cell are the delay of processing

- The Gary cells are fine

- The blue is the special packets . The Packet Packet Unit expect more packet .. so more delay

might affect the processing packet

Table 6.5: Packet processing for receiving side when the RISC clock is 752 MHz and the DMA

is 3759

Packet

size

Total Budget

time required for

100 Gbps (ns)

TCP Processing time at

PPU Different time

Single Segment

Message

1500bytes

123.00 32 -91

1024

bytes 83.50 28.1 -55.4

512

bytes42.60 34.5 -8.1

256

bytes 22.10 27.52 5.42

128

bytes 11.80 21.76 9.96

64 bytes 6.72 21.76 15.04

Singling 64 6.72 12.8 6.08

Continuation of

Message

1500 123.00 37.12 -85.88

1024 83.50 37.12 -46.38

512 42.60 39.68 -2.92

End of Message

1500 123.00 39.68 -83.32

1024 83.50 35.84 -47.66

512 42.60 39.68 -2.92

256 22.10 35.84 13.74

128 11.80 35.84 24.04

64 6.72 23.04 16.34

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When the RISC hertz increase to 1449 … there is no delay only when the 64 bytes

Table 6.6: LRO packet processing time for receive size when the RISC clock is 1449 MHz and

the DMA is 3759

Packet

size

Total Budget

time required for

100 Gbps (ns)


PPU Different time

Single Segment

Message (SSM)

1024 83.50 14.025 -69.475

512 42.60 17.2125 -25.3875

256 22.10 13.3875 -8.7125

128 11.80 10.8375 -0.9625

64 6.72 10.8375 4.1175

Singling 64 67.20 5.1 -1.62

Continuation of Message

1500 123.00 18.4875 -104.5125

1024 83.50 18.4875 -65.0125

512 42.60 19.7625 -22.8375

End of Message

1500 123.00 19.7625 -103.2375

1024 83.50 17.85 -65.65

512 42.60 19.7625 -2.28E+01

256 22.10 17.85 -4.25

128 11.80 17.85 6.05

64 6.72 10.8375 4.1375

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Table 6.7: packet processing time for Sending Side when the RISC clock is 752 MHz and the

DMA is 3759

Packet

size

Total Budget

time required for

100 Gbps (ns)


PPU Different time

Single Segment

Message

1500 123.00 23.04 -99.96

1024 83.50 19.2 -64.3

512 42.60 23.04 -19.56

256 22.10 17.92 -4.18

128 11.80 14.08 2.28

64 6.72 12.8 6.08 Singling 64 67.20 6.4 -0.32

Continuation of

Message

1500 123.00 17.92 -105.08

1024 83.50 14.08 -69.42

512 42.60 20.48 -22.12

End of Message

1500 123.00 19.2 -103.8

1024 83.50 14.08 -69.42

512 42.60 21.76 -2.08E+01

256 22.10 14.08 -8.02

128 11.80 11.52 -0.28

64 6.72 8.96 2.26

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Table 6.8: LSO packet processing sending side time when the RISC clock is 1449 MHz and the

DMA is 3759

Packet

size

Total Budget

time required for

100 Gbps (ns)


PPU

Different time

Single Segment

Message

1500 123.00 11.475 -111.525

1024 83.50 9.5625 -73.9375

512 42.60 11.475 -31.125

256 22.10 8.925 -13.175

128 11.80 7.0125 -4.7875

64 6.72 6.375 -0.345

Singling 64 6.72 3.1875 -3.5325

Continuation of

Message

1500 123.00 8.925 -114.075

1024 83.50 7.0125 -76.4875

512 42.60 10.2 -32.4

End of Message

1500 123.00 9.5625 -113.4375

1024 83.50 7.0125 -76.4875

512 42.60 10.8375 -3.18E+01

256 22.10 7.0125 -15.0875

128 11.80 5.7375 -6.0625

64 6.72 4.4625 -2.2375

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GAF 4957977 Last Part