On 09/10, Tariq Toukan wrote: > From: Cosmin Ratiu <cratiu@xxxxxxxxxx> > > Use the new devlink param to control how many doorbells mlx5e devices > allocate and use. The maximum number of doorbells configurable is capped > to the maximum number of channels. This only applies to the Ethernet > part, the RDMA devices using mlx5 manage their own doorbells. > > Signed-off-by: Cosmin Ratiu <cratiu@xxxxxxxxxx> > Reviewed-by: Dragos Tatulea <dtatulea@xxxxxxxxxx> > Signed-off-by: Tariq Toukan <tariqt@xxxxxxxxxx> > --- > Documentation/networking/devlink/mlx5.rst | 8 ++++++ > .../net/ethernet/mellanox/mlx5/core/devlink.c | 26 +++++++++++++++++++ > .../ethernet/mellanox/mlx5/core/en_common.c | 15 ++++++++++- > 3 files changed, 48 insertions(+), 1 deletion(-) > > diff --git a/Documentation/networking/devlink/mlx5.rst b/Documentation/networking/devlink/mlx5.rst > index 60cc9fedf1ef..0650462b3eae 100644 > --- a/Documentation/networking/devlink/mlx5.rst > +++ b/Documentation/networking/devlink/mlx5.rst > @@ -45,6 +45,14 @@ Parameters > - The range is between 1 and a device-specific max. > - Applies to each physical function (PF) independently, if the device > supports it. Otherwise, it applies symmetrically to all PFs. > + * - ``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`? 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?
