netdev - Re: [net-next 08/16] net/mlx5e: Add devlink fdb_large

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Date:   Mon, 2 Mar 2020 02:04:20 +0000
From:   Jianbo Liu <jianbol@...lanox.com>
To:     Jakub Kicinski <kuba@...nel.org>
Cc:     Saeed Mahameed <saeedm@...lanox.com>,
        "David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
        Vlad Buslov <vladbu@...lanox.com>,
        Roi Dayan <roid@...lanox.com>, Jiri Pirko <jiri@...lanox.com>
Subject: Re: [net-next 08/16] net/mlx5e: Add devlink fdb_large_groups
 parameter

The 02/28/2020 11:10, Jakub Kicinski wrote:
> On Thu, 27 Feb 2020 16:44:38 -0800 Saeed Mahameed wrote:
> > From: Jianbo Liu <jianbol@...lanox.com>
> > 
> > Add a devlink parameter to control the number of large groups in a
> > autogrouped flow table. The default value is 15, and the range is between 1
> > and 1024.
> > 
> > The size of each large group can be calculated according to the following
> > formula: size = 4M / (fdb_large_groups + 1).
> > 
> > Examples:
> > - Set the number of large groups to 20.
> >     $ devlink dev param set pci/0000:82:00.0 name fdb_large_groups \
> >       cmode driverinit value 20
> > 
> >   Then run devlink reload command to apply the new value.
> >     $ devlink dev reload pci/0000:82:00.0
> > 
> > - Read the number of large groups in flow table.
> >     $ devlink dev param show pci/0000:82:00.0 name fdb_large_groups
> >     pci/0000:82:00.0:
> >       name fdb_large_groups type driver-specific
> >         values:
> >           cmode driverinit value 20
> > 
> > Signed-off-by: Jianbo Liu <jianbol@...lanox.com>
> > Reviewed-by: Vlad Buslov <vladbu@...lanox.com>
> > Reviewed-by: Roi Dayan <roid@...lanox.com>
> > Acked-by: Jiri Pirko <jiri@...lanox.com>
> > Signed-off-by: Saeed Mahameed <saeedm@...lanox.com>
> 
> Slicing memory up sounds like something that should be supported via
> the devlink-resource API, not by params and non-obvious calculations :(

No, it's not to configure memory resource. It is to control how many
large groups in FW FDB. The calculations to to tell how many rules in each
large group.

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