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Question

I have to add scrambler for skb->data(socket buffer). When I try to scramble each byte in skb->data, the speed decreases 10 times.

for (i = 0; i < skb->len; i++){
    skb->data[i] = skb->data[i]^lfsr[i];                   
}

How can I scramble skb->data faster? Update: How can i scramble more than one byte in one iteration?

Answer

You can remove the pointer dereferencing, use in-place memory manipulation, and use OpenMP to parallelize the loop, like so:

//Compile with -fopenmp flag
const int len  = skb->len;
auto &data = skb->data;
#pragma omp parallel for simd
for(int i=0;i<len;i++)
    data[i] ^= lfsr[i];