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

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Message-ID: <20180109160646.GA2262@C02RW35GFVH8.dhcp.broadcom.net>
Date:   Tue, 9 Jan 2018 11:06:46 -0500
From:   Andy Gospodarek <andy@...yhouse.net>
To:     Saeed Mahameed <saeedm@...lanox.com>
Cc:     netdev@...r.kernel.org, mchan@...adcom.com, talgi@...lanox.com,
        ogerlitz@...lanox.com, Andy Gospodarek <gospo@...adcom.com>
Subject: Re: [PATCH net-next v3 06/10] net/mlx5e: Change Mellanox references
 in DIM code

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.


> >   	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;
> >   }