Hi Jun, On Tue, Feb 10, 2026 at 8:54 AM jun.gu via discuss <[email protected]> wrote: > > Hi, > > We are currently observing packet drops when `ovn-controller` restarts. > Our environment is running OVN 21.09 and OVS 2.16.2. > > We reviewed commit d53c599ed05ea3c708a045a9434875458effa21e, which > avoids dataplane downtime during the initial flow installation. However, > it appears that this change does not fully eliminate packet drops during > an `ovn-controller` restart, as the flow clearing operation still exists. > > We also looked at commit 358b1dd53dcd9dde28f47caa21ea19e755323705, which > ensures that all monitored updates are received before installing flows. > Based on these two commits, we are considering a potential optimization > in `ofctl.c`: > - In `run_S_NEW()`: modify the cookie ID of all existing flows to a > unified value (e.g., `0x1234`). > - In `ofctrl_put()`: remove the `clear flows` and `clear groups` operations. > - In `recv_S_UPDATE_FLOWS()`: delete redundant flows whose cookie ID was > set in `run_S_NEW()`. >
The flag ovn-ofctrl-wait-before-clear was launched a few OVN releases ago (I am not sure if it was OVN 22.03)for this purpose to delay to clear the flows. https://github.com/ovn-org/ovn/commit/4a34b878d02464266c2b7ff2779de121b130e065 For me it has worked well since then using /usr/share/ovn/scripts/ovn-ctl stop_controller --restart and upgrading the ovn-controller. Since you are using an old version maybe you could consider upgrading it. The flag ovn-ofctrl-wait-before-clear was removed recently since there is another mechanism to handle it. > The goal is to avoid clearing flows during restart while still ensuring > stale flows are properly cleaned up once updated flows are installed. > > Please let us know if this approach makes sense. If there are no > objections, we would like to prepare and submit a patch for further > discussion. > > Best regards, > Jun Regards, Tiago Pires > > _______________________________________________ > discuss mailing list > [email protected] > https://mail.openvswitch.org/mailman/listinfo/ovs-discuss -- _‘Esta mensagem é direcionada apenas para os endereços constantes no cabeçalho inicial. Se você não está listado nos endereços constantes no cabeçalho, pedimos-lhe que desconsidere completamente o conteúdo dessa mensagem e cuja cópia, encaminhamento e/ou execução das ações citadas estão imediatamente anuladas e proibidas’._ * **‘Apesar do Magazine Luiza tomar todas as precauções razoáveis para assegurar que nenhum vírus esteja presente nesse e-mail, a empresa não poderá aceitar a responsabilidade por quaisquer perdas ou danos causados por esse e-mail ou por seus anexos’.* _______________________________________________ discuss mailing list [email protected] https://mail.openvswitch.org/mailman/listinfo/ovs-discuss
