netdev - Re: [PATCH net-next v3 06/10] net/mlx5e: Change Mellanox references in DIM code

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Date:   Tue, 9 Jan 2018 14:38:46 -0500
From:   Andy Gospodarek <andy@...yhouse.net>
To:     Tal Gilboa <talgi@...lanox.com>
Cc:     Saeed Mahameed <saeedm@...lanox.com>, netdev@...r.kernel.org,
        mchan@...adcom.com, Talat Batheesh <talatb@...lanox.com>
Subject: Re: [PATCH net-next v3 06/10] net/mlx5e: Change Mellanox references
 in DIM code

On Tue, Jan 09, 2018 at 08:22:15PM +0200, Tal Gilboa wrote:
> On 1/9/2018 6:06 PM, Andy Gospodarek wrote:
> > On Mon, Jan 08, 2018 at 11:06:28PM -0800, Saeed Mahameed wrote:
> > > 
> > > 
> > > On 01/08/2018 10:13 PM, Andy Gospodarek wrote:
> > > > From: Andy Gospodarek <gospo@...adcom.com>
> > > > 
> > > > Change all appropriate mlx5_am* and MLX5_AM* references to net_dim and
> > > > NET_DIM, respectively, in code that handles dynamic interrupt
> > > > moderation.  Also change all references from 'am' to 'dim' when used as
> > > > local variables and add generic profile references.
> > > > 
> > > > Signed-off-by: Andy Gospodarek <gospo@...adcom.com>
> > > > Acked-by: Tal Gilboa <talgi@...lanox.com>
> > > > Acked-by: Saeed Mahameed <saeedm@...lanox.com>
> > > > ---
> > > >    drivers/net/ethernet/mellanox/mlx5/core/en.h       |   9 +-
> > > >    drivers/net/ethernet/mellanox/mlx5/core/en_dim.c   |  14 +-
> > > >    .../net/ethernet/mellanox/mlx5/core/en_ethtool.c   |   6 +-
> > > >    drivers/net/ethernet/mellanox/mlx5/core/en_main.c  |  40 ++-
> > > >    drivers/net/ethernet/mellanox/mlx5/core/en_txrx.c  |   8 +-
> > > >    drivers/net/ethernet/mellanox/mlx5/core/net_dim.c  | 286 ++++++++++-----------
> > > >    drivers/net/ethernet/mellanox/mlx5/core/net_dim.h  |  63 ++---
> > > >    7 files changed, 225 insertions(+), 201 deletions(-)
> > > > 
> > > 
> > > [...]
> > > 
> > > >    #define IS_SIGNIFICANT_DIFF(val, ref) \
> > > >    	(((100 * abs((val) - (ref))) / (ref)) > 10) /* more than 10% difference */
> > > > -static int mlx5e_am_stats_compare(struct mlx5e_rx_am_stats *curr,
> > > > -				  struct mlx5e_rx_am_stats *prev)
> > > > +static int net_dim_stats_compare(struct net_dim_stats *curr,
> > > > +				 struct net_dim_stats *prev)
> > > >    {
> > > >    	if (!prev->bpms)
> > > > -		return curr->bpms ? MLX5E_AM_STATS_BETTER :
> > > > -				    MLX5E_AM_STATS_SAME;
> > > > +		return curr->bpms ? NET_DIM_STATS_BETTER :
> > > > +				    NET_DIM_STATS_SAME;
> > > >    	if (IS_SIGNIFICANT_DIFF(curr->bpms, prev->bpms))
> > > > -		return (curr->bpms > prev->bpms) ? MLX5E_AM_STATS_BETTER :
> > > > -						   MLX5E_AM_STATS_WORSE;
> > > > +		return (curr->bpms > prev->bpms) ? NET_DIM_STATS_BETTER :
> > > > +						   NET_DIM_STATS_WORSE;
> > > 
> > > Hey Andy,
> > > 
> > > I am currently reviewing a patch internally that fixes a bug in this area,
> > > prev->ppms can be 0 and could cause IS_SIGNIFICANT_DIFF ouch !
> > > same goes for prev->eppm, for some reason we had a broken assumption that if
> > > ppms is 0 for some reason then the bpms is 0 and the above condition will
> > > cover us.
> > > 
> > > Anyway the patch will go to net, which means when this series gets accepted
> > > then net-next will fail to merge with net and we need to manually push the
> > > fix to the new DIM library.
> > > 
> > > But for now I don't think anything is required for this series other than
> > > bringing this division by 0 issue and the future merge conflict to your
> > > attention.
> > > 
> > 
> > Thanks for bringing that to everyone's attention.  I agree there is
> > probably not much that should be done at this point -- hopefully the
> > merge should go pretty smoothly, since net_dim.h is seen as a rename
> > from en_rx_am.c.
> 
> I talked with Talat, who is submitting the fix. He will apply it over these
> patches after they are accepted.
> 

Awesome!  Thanks for doing that.  v4 coming in a few mins -- hopefully the
last.  :-)

> > 
> > 
> > > >    	if (IS_SIGNIFICANT_DIFF(curr->ppms, prev->ppms))
> > > > -		return (curr->ppms > prev->ppms) ? MLX5E_AM_STATS_BETTER :
> > > > -						   MLX5E_AM_STATS_WORSE;
> > > > +		return (curr->ppms > prev->ppms) ? NET_DIM_STATS_BETTER :
> > > > +						   NET_DIM_STATS_WORSE;
> > > >    	if (IS_SIGNIFICANT_DIFF(curr->epms, prev->epms))
> > > > -		return (curr->epms < prev->epms) ? MLX5E_AM_STATS_BETTER :
> > > > -						   MLX5E_AM_STATS_WORSE;
> > > > +		return (curr->epms < prev->epms) ? NET_DIM_STATS_BETTER :
> > > > +						   NET_DIM_STATS_WORSE;
> > > > -	return MLX5E_AM_STATS_SAME;
> > > > +	return NET_DIM_STATS_SAME;
> > > >    }