[BeeOnRope]

It's easy to see both sides here. The overwhelming majority of code is not written to be run a in a kernel at the kernel-user security boundary, so for most code paying something to initialize padding might not be a great tradeoff. That is, the vast majority of code is running within a single security domain and doesn't need to protect itself from itself.

Still, avoiding initializing padding is probably not a great example of a performance win through standards exploitation: in the example given it's not clear why you'd not just do one 8 byte zeroing write to cover the whole structure, rather than apparently splitting it into a 4-byte and a 1-byte write. Perhaps this was 32-bit code, where 8-byte write are slightly trickier, but even two 4-byte writes are likely to perform just as well or better. Probably it's just bad codegen to treat the initialization of the struct[11] in two parts: a single struct and a 10-member array.