On Wed, May 20, 2026 at 3:20 AM Robin Jarry <[email protected]> wrote: > > Hi Jerin, > > Jerin Jacob, May 19, 2026 at 12:25: > > Some high-level comments: > > > > 1)What will be the performance overhead for graph walk. Try > > app/test/test_graph_perf.c and l3fwd_graph > > I have made some measurements. There was a regression caused by > systematic access to a cache line. This will be fixed in v2.
Thanks. We will review the v2. > > 2)If priorities are same, Does it have similar performance with > > existing code? > > Yes with v2. I have added a topo order as a fallback when all priorities > are equal so that it behaves as previously. > > > 3)Does it have any effect on packet ordering on egress.i.e for a given > > flow ingress order != egress order > > Some independent flows "may" be reordered but that depends on the > topology, not the graph walk algorithm. > > For example, the following graph: > > +--------+ > | eth_in | > +--------+ > / \ > v v > +-------+ +---------+ > | ip_in | <-- | mpls_in | > +-------+ +---------+ > | > | ,------------. > v v | > +--------+ +----------+ > | ip_out | --> | ipip_out | > +--------+ +----------+ > | > v > +---------+ > | eth_out | > +---------+ > > If you receive the following stream of packets in "eth_in": > > 1. Eth/IP > 2. Eth/IP > 3. Eth/MPLS/IP > 4. Eth/MPLS/IP > 5. Eth/MPLS/IP > 6. Eth/IP (needs IPIP encap) > 7. Eth/IP (needs IPIP encap) > 8. Eth/IP > > The "eth_out" node will see: > > 1. Eth/IP > 2. Eth/IP > 3. Eth/IP > 4. Eth/IP > 5. Eth/IP > * 8. Eth/IP <----------- reordered before 6 and 7 > 6. Eth/IP/IP > 7. Eth/IP/IP > > With the FIFO circular buffer and with the new bitmap priority scheduler. > > The only difference with the bitmap system is that If you set "mpls_in" > and "ip_out" higher priorities, the "ip_in" and "eth_out" nodes will be > visited only once. > > > If there is performance regression we may need to consider new > > RTE_GRAPH_MODEL_XXXXX to enable this feature > > > -- > Robin > > > Times approximate. >
