On Wed, Sep 10, 2025 at 09:16:40AM -0700, Stanislav Fomichev wrote: > > + * - ``num_doorbells`` > > + - driverinit > > + - This controls the number of channel doorbells used by the netdev. In all > > + cases, an additional doorbell is allocated and used for non-channel > > + communication (e.g. for PTP, HWS, etc.). Supported values are: > > + - 0: No channel-specific doorbells, use the global one for everything. > > + - [1, max_num_channels]: Spread netdev channels equally across these > > + doorbells. > > Do you have any guidance on this number? Why would the user want > `num_doorbells < num_doorbells` vs `num_doorbells == num_channels`? I expect it to be common that most deployment should continue to use the historical value of num_doorbells = 0. Certain systems with troubled CPUs will need to increase this, I don't know if we yet fully understand what values these CPUs will need. Nor do I think I'm permitted to say what CPUs are troubled :\ > IOW, why not allocate the same number of doorbells as the number of > channels and do it unconditionally without devlink param? Are extra > doorbells causing any overhead in the non-contended case? It has a cost that should be minimized to not harm the current majority of users. Jason
