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David S. Miller authored
We burn a lot of useless cycles, cpu store buffer traffic, and memory operations memset()'ing the on-stack flow used to perform output route lookups in __ip_route_output_key(). Only the first half of the flow object members even matter for output route lookups in this context, specifically: FIB rules matching cares about: dst, src, tos, iif, oif, mark FIB trie lookup cares about: dst FIB semantic match cares about: tos, scope, oif Therefore only initialize these specific members and elide the memset entirely. On Niagara2 this kills about ~300 cycles from the output route lookup path. Likely, we can take things further, since all callers of output route lookups essentially throw away the on-stack flow they use. So they don't care if we use it as a scratch-pad to compute the final flow key. Signed-off-by:
David S. Miller <davem@davemloft.net> Acked-by:
Eric Dumazet <eric.dumazet@gmail.com>
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