28/10/2020 11:24, Van Haaren, Harry: > From: Thomas Monjalon > > > + IP4_LOOKUP_NODE_PRIV1_OFF(node->ctx) = node_mbuf_priv1_dynfield_offset; > > > > That's interesting. > > You copy the offset in the node context for better performance. > > How much is it better than with global offset variable? > > How much it decreases compared to a static mbuf field? > > Also interested in this topic, I'll offer the logical/theory point of view; > > With a static field, the offset into the mbuf can be encoded in the > instruction > stream, meaning there are no d-cache loads to identify particular dynamic > field. > > With a static/global variable, the cache line where the value resides is > presumably > not hot in cache per burst (assuming an application that does significant > work, so not > in cache since last burst). Hence overhead estimate could be 1x cache line > load per burst.
Would it help to group all dynfields and dynflags offsets in the same cache line?
