Re: [Intel-wired-lan] [iwl-next] ice, irdma: Add rdma_qp_limits_sel devlink parameter for irdma

[Leon Romanovsky <leon@kernel.org>]

On Wed, Sep 10, 2025 at 09:41:14AM +0200, Przemek Kitszel wrote:
> On 9/9/25 14:20, Leon Romanovsky wrote:
> > On Thu, Sep 04, 2025 at 02:57:19PM -0500, Tatyana Nikolova wrote:
> > > Add a devlink parameter to switch between different QP resource profiles
> > > (max number of QPs) supported by irdma for Intel Ethernet 800 devices. The
> > > rdma_qp_limits_sel is translated into an index in the rsrc_limits_table to
> > > select a power of two number between 1 and 256 for max supported QPs (1K-256K).
> > > To reduce the irdma memory footprint, set the rdma_qp_limits_sel default value
> > > to 1 (max 1K QPs).
> > > 
> > > Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
> > > Signed-off-by: Tatyana Nikolova <tatyana.e.nikolova@intel.com>
> > > ---
> > > Since the changes to irdma are minor, this is targeted to iwl-next/net-next.
> > 
> > <...>
> > 
> > >   #define DEVLINK_LOCAL_FWD_DISABLED_STR "disabled"
> > >   #define DEVLINK_LOCAL_FWD_ENABLED_STR "enabled"
> > >   #define DEVLINK_LOCAL_FWD_PRIORITIZED_STR "prioritized"
> > > @@ -1621,6 +1723,7 @@ enum ice_param_id {
> > >   	ICE_DEVLINK_PARAM_ID_BASE = DEVLINK_PARAM_GENERIC_ID_MAX,
> > >   	ICE_DEVLINK_PARAM_ID_TX_SCHED_LAYERS,
> > >   	ICE_DEVLINK_PARAM_ID_LOCAL_FWD,
> > > +	ICE_DEVLINK_PARAM_ID_RDMA_QP_LIMITS_SEL,
> > >   };
> > 
> > I was under impression that driver-specific devlink knobs are not
> > allowed. Was this limitation changed for Intel?
> 
> I'm not aware of such limitation.

It is possible that my impression was wrong.

> It's always better to have generic params, but some knobs are not likely
> to be reused; anyway it would be easy to convert into generic.

Unlikely, you will need to keep old parameter and new at the same time
for backward compatibility reasons.

> 
> To have this particular param more generic-ready, we have converted from
> our internal format (values were 0...7, mapped into some powers of two)
> to what one could imagine other drivers would like to add at some point
> (perhaps multiplying the user-provided value by 1K is unnecessarily
> complicating adoption for small NICs, IDK?).
> 
> Do you believe this should be switched to generic now (instead of when
> there is a future user)?
> What about a name (this should be kept forever)?

mlx5 has .log_max_qp in mlx5_profile which looks similar to what you are
proposing here, so RDMA_QP_LIMITS sounds fine to me.

> 
> side note:
> We are also going to add yet another param, now used only by intel, but
> we do so as a generic one: "max number of MAC addrs for VF in i40e", see
> https://lore.kernel.org/intel-wired-lan/20250907100454.193420-1-mheib@redhat.com/T/#t
> 
> 
> > 
> > Thanks
>