Re: [RFC] Documentation about unaligned memory access

Johannes Berg
2007-11-26T15:48:25Z

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> Sidenote: in the above example, you may wish to reorder the fields in the
> above structure so that the overall structure uses less memory. For example,
> moving field3 to sit inbetween field1 and field2 (where the padding is
> inserted) would shrink the overall structure by 1 byte:
>
> struct foo {
> u16 field1;
> u8 field3;
> u32 field2;
> };

You can reorder to u32, u16, u8 order and save another byte :)

A reference to pahole could be appropriate here, and probably a small
note that some large existing structures like netdev have deliberate
holes to achieve cache alignment.

johannes

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