MOTOROLA
Chapter 3. DINK32 Commands
3-11
Benchmark
3.7
Benchmark
The “benchmark” command will display how many timebase ticks it takes to execute the
user code at ‘a(chǎn)ddress’. This command will take multiple passes at the benchmark with
different processor configurations. It will report the timebase ticks on each configuration.
If the timebase register is reported to be ‘0x00000000 00000000’ check to see if it is
followed by a ‘.’. If it is, then this means that the benchmark actually took less time than it
took to measure how long it took just to get to the beginning of the benchmark (which is
used as a base run and subtracted out of the full run before being displayed on screen).
The result of the benchmark can be converted to seconds by the following formula. These
results are time base clicks, which for the MPC7400 (UM p. 2-8) is one fourth the bus rate.
So (benchmark tics * 4) * 1/50000000 at 100 Mhz for the MPC7400. Each processor has
it’s own specification, which is shown in the appropriate UM (User’s Manual).
Thus, for the MPC7400, the time base increments once for every four bus cycles. The
formula is: ((benchmark tics * 4) * 40 nanoseconds) for a 100 Mhz clock. Thus for this test,
the results of the last configuration, Icache ON Dcache ON, we got 0x1b26e18c time base
tics, which is 455,532,940 decimal time tics. Applying our formula (455,532,940 * 4) *
0.00000004 is 72.88 seconds. This is reasonable for this test, because it displays a series of
displays each separated by a wait loop.
This command requires that the User Code (to be benchmarked) be terminated with an
illegal opcode!
More discussion on “Bus Speed” for the sandpoint. There are three clock speeds that
determine the system performance:
PCI Bus Speed
System (Memory/CPU) Bus Speed
Processor Core Speed
We usually refer to these as, say, 400/100/33 indicating a 400 MHz CPU w/a 100 MHz
system bus and 33 MHz PCI. The PCI bus should be running at 33 MHz; no other bus speed
is supported on SP X2. If the board is misconfigured, it might be in 66 MHz -- make sure
the PCI66MHZ LED is OFF. It is unlikely your system would run at all, if that were so.
Command
benchmark
Abbreviation
bm
Syntax
bn address
Builds
DINK
Boards
All
Processors
All
F
Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
n
.