net: sctp: Optimise the way 'sctp_arg_t' values are initialised.
Even if memset() is inlined (as on x86) using it to zero the union generates a memory word write of zero, followed by a write of the smaller field, and then a read of the word. As well as being a lot of instructions the sequence is unlikely to be optimised by the store-load forward hardware so will be slow. Instead allocate a field of the union that is the same size as the entire union and write a zero value to it. The compiler will then generate the required value in a register. Zeroing the union shouldn't be necessary, but this patch series isn't intended to have a behavioural change. Signed-off-by: David Laight <david.laight@aculab.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Please register or sign in to comment