Flash program memory and data EEPROM (FLASH) RM0367
80/1043 RM0367 Rev 7
Dhrystone performances
The Dhrystone test is used to evaluate the memory interface performances. The test has
been executed in all memory interface configurations. Refer to Table 16 for a summary of
the results.
Common parameters are:
• the matrix size is 20 x 20
• the loop is executed 1757 times
• the version of Arm
®
compiler is 4.1 [Build 561]
Here is some explanation about the results:
• The pre-read is not useful for this test: when enabled with the prefetch, it reduces the
memory interface performance because only one buffer is used to store the last data
read and, in this code, the master rarely reads the data linearly. This justifies the very
small increase of performance when enabled without a prefetch.
• The buffers (without speculative readings) with 1 wait state give a little advantage that
can be considered without any costs.
• At a 0 wait state, the best performance (as certified by Arm
®
) may be due to a different
code alignment during the compilation.
Table 16. Dhrystone performances in all memory interface configurations
Number of
wait states
DISAB_BUF PRFTEN PRE_READ
Number of
DMIPS (x1000)
DMIPS x MHz
0 1 0 0 953 15.25
0 0 0 0 953 15.25
0 0 1 0 953 15.25
0 0 0 1 953 15.25
0 0 1 1 953 15.25
1 1 0 0 677 21.66
1 0 0 0 690 22.08
1 0 1 0 823 26.34
100169122.11
101181626.11
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