4cd917b308
While some applications may store metadata about packets in the packet mbuf headroom, this is not a workable solution for packet metadata which is either: * larger than the headroom (or headroom is needed for adding pkt headers) * needs to be shared or copied among packets To support these use cases in applications, we reserve a general "userdata" pointer field inside the second cache-line of the mbuf. This is better than having the application store the pointer to the external metadata in the packet headroom, as it saves an additional cache-line from being used. Apart from storing metadata, this field also provides a general 8-byte scratch space inside the mbuf for any other application uses that are applicable. Signed-off-by: Bruce Richardson <bruce.richardson@intel.com> Acked-by: Pablo de Lara <pablo.de.lara.guarch@intel.com> |
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