Mathematical Model For Psd - Intel ARCHITECTURE IA-32 Reference Manual

IA-32 Intel® Architecture Optimization
N
inst
Consider the following example of a heuristic equation assuming that
parameters have the values as indicated:
psd =
where 60 corresponds to
The values of the parameters in the equation can be derived from the
documentation for memory components and chipsets as well as from
vendor datasheets.

Mathematical Model for PSD

The parameters used in the mathematics discussed are as follows:
psd
il
T
c
T
l
E-2
is the number of instructions in the scope of one loop
iteration.
⋅ (
+
60 25 N
pref
-----------------------------------------------------
⋅
1.5 N
inst
Nlookup
CAUTION.
illustration only and do not represent the actual values
for these parameters. The example is provided as a
"starting point approximation" of calculating the
prefetch scheduling distance using the above formula.
Experimenting with the instruction around the
"starting point approximation" may be required to
achieve the best possible performance
prefetch scheduling distance (measured in number of
iterations)
iteration latency
computation latency per iteration with prefetch caches
memory leadoff latency including cache miss latency,
chip set latency, bus arbitration, etc.
)
+
N
st
, 25 to
Nxfer
The values in this example are for
, and 1.5 to .
CPI
.