[ovs-dev] [PATCH net-next] udp: intoduce udp_encap_needed static_key
eric.dumazet at gmail.com
Thu Apr 12 02:10:11 PDT 2012
On Thu, 2012-04-12 at 11:05 +0200, Eric Dumazet wrote:
> If static_key is not yet enabled, the fast path does a single JMP .
> When static_key is enabled, JMP destination is patched to reach the real
> encap_type/encap_rcv logic, possibly adding cache misses.
Small note Simon,
The jump trick is effective on x86 (and maybe some other arches) when
Else, its replaced by atomic_read(...) > 0, a cnditional jump but
reading a read_mostly/shared variable, instead of a per socket field.
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