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| H A D | pktgen.c | diff 90149031325c06fadc806720d57171aacc74a5d7 Tue Aug 10 14:01:54 CDT 2021 Nick Richardson <richardsonnick@google.com> pktgen: Add imix distribution bins
In order to represent the distribution of imix packet sizes, a
pre-computed data structure is used. It features 100 (IMIX_PRECISION)
"bins". Contiguous ranges of these bins represent the respective
packet size of each imix entry. This is done to avoid the overhead of
selecting the correct imix packet size based on the corresponding weights.
Example:
imix_weights 40,7 576,4 1500,1
total_weight = 7 + 4 + 1 = 12
pkt_size 40 occurs 7/total_weight = 58% of the time
pkt_size 576 occurs 4/total_weight = 33% of the time
pkt_size 1500 occurs 1/total_weight = 9% of the time
We generate a random number between 0-100 and select the corresponding
packet size based on the specified weights.
Eg. random number = 358723895 % 100 = 65
Selects the packet size corresponding to index:65 in the pre-computed
imix_distribution array.
An example of the pre-computed array is below:
The imix_distribution will look like the following:
0 -> 0 (index of imix_entry.size == 40)
1 -> 0 (index of imix_entry.size == 40)
2 -> 0 (index of imix_entry.size == 40)
[...] -> 0 (index of imix_entry.size == 40)
57 -> 0 (index of imix_entry.size == 40)
58 -> 1 (index of imix_entry.size == 576)
[...] -> 1 (index of imix_entry.size == 576)
90 -> 1 (index of imix_entry.size == 576)
91 -> 2 (index of imix_entry.size == 1500)
[...] -> 2 (index of imix_entry.size == 1500)
99 -> 2 (index of imix_entry.size == 1500)
Create and use "bin" representation of the imix distribution.
Signed-off-by: Nick Richardson <richardsonnick@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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