> On Fri, 18 Oct 2024 03:21:28 +0000 > Chaoyong He <chaoyong...@corigine.com> wrote: > > > > RTE_PKTMBUF_HEADROOM); } > > > > + > > > > > > Not sure why this is needed? What is the problem with the original code? > > > Are you trying to force packets to be segmented? > > > > Actually, we are trying to force packets *not* segmented by making the > mbuf size large enough to hold the packets. > > > > In our user case, we start l3fwd app with parameter '--max-pkt-len 4000', > and obviously the original logic with RTE_MBUF_DEFAULT_DATAROOM mbuf > size will cause the packets to be segmented. > > Which is not what we want, so we add this new '--mbuf-size=4096' > parameter, the mbuf size will large enough to hold even the largest packet. > > > > Do you think this make sense? > > Maybe query the driver, and use the max_rx_pkt_len as input to deciding the > right mbuf size.
Sorry, I am not quite understanding here. I can't find 'max_rx_pkt_len' in l3fwd app, instead it's exist testpmd app. Could you please explain a little more about the advice? > If max-pkt-len was 4000 and driver can only take 2K buffers, then use 2K mbuf > size. > If max-pkt-len was 1500 then use mtu + headroom and round up
