https://oguzpastirmaci.com/tags/dpdk/Recent content in Dpdk on Under the ModelHugoen-USTue, 20 Oct 2026 00:00:00 +0000https://oguzpastirmaci.com/posts/why-large-roce-frames-disappeared-on-ovs-doca-3-5/Tue, 20 Oct 2026 00:00:00 +0000https://oguzpastirmaci.com/posts/why-large-roce-frames-disappeared-on-ovs-doca-3-5/<p>I looked into GB300 hosts where RDMA broke after an image update. <code>ib_write_bw</code> between two hosts worked with 512-byte messages. With 64 KiB messages, it showed 0 Gb/s. The links were up on the host and on the switch. Hosts on the older image worked.</p> <p>The cause was a small change in how OVS-DOCA reuses its receive buffer pools. On the new version, the pools kept the size for a 1500-byte MTU, although every port said 9216. RoCE frames of about 4.2 KB did not fit, and no counter called them dropped.</p>