linux-kernel - Re: [PATCH net-next v4 1/3] net/mlx4: Track RX allocation failures in a stat

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Date: Sun, 12 May 2024 11:37:20 -0700
From: Joe Damato <jdamato@...tly.com>
To: Tariq Toukan <ttoukan.linux@...il.com>
Cc: linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
	mkarsten@...terloo.ca, nalramli@...tly.com,
	Tariq Toukan <tariqt@...dia.com>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>,
	"open list:MELLANOX MLX4 core VPI driver" <linux-rdma@...r.kernel.org>
Subject: Re: [PATCH net-next v4 1/3] net/mlx4: Track RX allocation failures
 in a stat

On Sun, May 12, 2024 at 11:17:09AM +0300, Tariq Toukan wrote:
> 
> 
> On 09/05/2024 23:50, Joe Damato wrote:
> > mlx4_en_alloc_frags currently returns -ENOMEM when mlx4_alloc_page
> > fails but does not increment a stat field when this occurs.
> > 
> > A new field called alloc_fail has been added to struct mlx4_en_rx_ring
> > which is now incremented in mlx4_en_rx_ring when -ENOMEM occurs.
> > 
> > Signed-off-by: Joe Damato <jdamato@...tly.com>
> > Tested-by: Martin Karsten <mkarsten@...terloo.ca>
> > ---
> >   drivers/net/ethernet/mellanox/mlx4/en_rx.c   | 4 +++-
> >   drivers/net/ethernet/mellanox/mlx4/mlx4_en.h | 1 +
> >   2 files changed, 4 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/net/ethernet/mellanox/mlx4/en_rx.c b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
> > index 8328df8645d5..15c57e9517e9 100644
> > --- a/drivers/net/ethernet/mellanox/mlx4/en_rx.c
> > +++ b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
> > @@ -82,8 +82,10 @@ static int mlx4_en_alloc_frags(struct mlx4_en_priv *priv,
> >   	for (i = 0; i < priv->num_frags; i++, frags++) {
> >   		if (!frags->page) {
> > -			if (mlx4_alloc_page(priv, frags, gfp))
> > +			if (mlx4_alloc_page(priv, frags, gfp)) {
> > +				ring->alloc_fail++;
> >   				return -ENOMEM;
> > +			}
> >   			ring->rx_alloc_pages++;
> >   		}
> >   		rx_desc->data[i].addr = cpu_to_be64(frags->dma +
> > diff --git a/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h b/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
> > index efe3f97b874f..cd70df22724b 100644
> > --- a/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
> > +++ b/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
> > @@ -355,6 +355,7 @@ struct mlx4_en_rx_ring {
> >   	unsigned long xdp_tx;
> >   	unsigned long xdp_tx_full;
> >   	unsigned long dropped;
> > +	unsigned long alloc_fail;
> >   	int hwtstamp_rx_filter;
> >   	cpumask_var_t affinity_mask;
> >   	struct xdp_rxq_info xdp_rxq;
> 
> Counter should be reset in mlx4_en_clear_stats().

OK, thanks. I'll add that to the v5, alongside any other feedback that
comes in within the next ~24 hours or so.

> BTW, there are existing counters that are missing there already.
> We should add them as well, not related to your series though...

Yea, I see what you mean about the other counters. I think those can
potentially be sent as a 'Fixes' later?