AN2761 Freescale Semiconductor / Motorola, AN2761 Datasheet - Page 2

• Manufacturer Part Number: AN2761
• Description: Understanding Cryptographic Performance
• Manufacturer: Freescale Semiconductor / Motorola

Coldfire Security Performance
be scaled by the percentage of the bus that can be allocated to cryptographic processing, usually between
10% to 33%.
1.3
CPU limited performance takes into consideration the instructions per packet needed for protocol and
driver processing. CPU bandwidth limitations are estimated by multiplying CPU frequency by the CPU’s
instructions per clock and then dividing by the estimated instructions per packet. The instructions per
packet for IPSec processing, including driver overhead, is highly implementation dependent, but for the
purpose of this analysis, is estimated to vary between 6000-10000 IPP. The CPU limit should then be
scaled by the percentage of the CPU that can be dedicated to protocol processing, typically 40% to 75%.
The packets per second estimate is then multiplied by packet size to determine throughput in Mbps.
1.4
The overall system performance will therefore be the smaller of the three numbers for any given packet
size. Performance tends to be core limited at small packet sizes, bus limited at large packet sizes and
potentially limited by the cryptographic core in some high performance systems. Freescale Semiconductor
strives to not only provide the highest credibility performance number, but to demonstrate a methodology
that any customer can apply to their specific system.
2
Table 1 shows the security performance for Coldfire.
2
6000 IPP, 40%CPU
6000 IPP, 75% CPU
7500 IPP, 40%CPU
7500 IPP, 75% CPU
10000 IPP, 40%CPU
10000 IPP, 75% CPU
33% BUS Bandwidth
Security Raw Performance
CPU Limited Performance
Overall System Performance
Coldfire Security Performance
Measurement Point
Freescale Semiconductor, Inc.
Understanding Cryptographic Performance, Rev. 0
For More Information On This Product,
64B [Mbps]
Table 1. 266 MHz CPU, 266MHz Bus
166.3
352.0
13.6
25.5
10.9
20.4
15.3
8.2
Go to: www.freescale.com
[Mbps]
128B
240.8
352.0
27.2
51.1
21.8
40.9
16.3
30.6
[Mbps]
102.1
310.4
352.0
256B
54.5
43.6
81.7
32.7
61.3
[Mbps]
109.0
204.3
163.4
122.6
362.8
352.0
512B
87.2
65.4
[Mbps]
1024B
217.9
408.6
174.3
326.9
130.7
245.1
396.3
352.0
Freescale Semiconductor
[Mbps]
1536B
326.9
612.9
261.5
490.3
196.1
367.7
408.8
352.0