Re: [PATCH rdma-next v1 3/4] RDMA/nldev: Provide MR statistics

From: Jason Gunthorpe <jgg@mellanox.com>
To: Leon Romanovsky <leon@kernel.org>
Cc: Doug Ledford <dledford@redhat.com>,
	Leon Romanovsky <leonro@mellanox.com>,
	RDMA mailing list <linux-rdma@vger.kernel.org>,
	Erez Alfasi <ereza@mellanox.com>
Subject: Re: [PATCH rdma-next v1 3/4] RDMA/nldev: Provide MR statistics
Date: Mon, 9 Sep 2019 08:51:50 +0000	[thread overview]
Message-ID: <20190909085148.GD2843@mellanox.com> (raw)
In-Reply-To: <20190830081612.2611-4-leon@kernel.org>

On Fri, Aug 30, 2019 at 11:16:11AM +0300, Leon Romanovsky wrote:
> From: Erez Alfasi <ereza@mellanox.com>
> 
> Add RDMA nldev netlink interface for dumping MR
> statistics information.
> 
> Output example:
> ereza@dev~$: ./ibv_rc_pingpong -o -P -s 500000000
>   local address:  LID 0x0001, QPN 0x00008a, PSN 0xf81096, GID ::
> 
> ereza@dev~$: rdma stat show mr
> dev mlx5_0 mrn 2 page_faults 122071 page_invalidations 0
> prefetched_pages 122071
> 
> Signed-off-by: Erez Alfasi <ereza@mellanox.com>
> Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
>  drivers/infiniband/core/device.c  |  1 +
>  drivers/infiniband/core/nldev.c   | 54 +++++++++++++++++++++++++++++--
>  drivers/infiniband/hw/mlx5/main.c | 16 +++++++++
>  include/rdma/ib_verbs.h           |  9 ++++++
>  4 files changed, 78 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/infiniband/core/device.c b/drivers/infiniband/core/device.c
> index 99c4a55545cf..34a9e37c5c61 100644
> +++ b/drivers/infiniband/core/device.c
> @@ -2610,6 +2610,7 @@ void ib_set_device_ops(struct ib_device *dev, const struct ib_device_ops *ops)
>  	SET_DEVICE_OP(dev_ops, get_dma_mr);
>  	SET_DEVICE_OP(dev_ops, get_hw_stats);
>  	SET_DEVICE_OP(dev_ops, get_link_layer);
> +	SET_DEVICE_OP(dev_ops, fill_odp_stats);
>  	SET_DEVICE_OP(dev_ops, get_netdev);
>  	SET_DEVICE_OP(dev_ops, get_port_immutable);
>  	SET_DEVICE_OP(dev_ops, get_vector_affinity);

I'm now curious what motivated placing the line here, apparently
randomly in a sorted list?

> +static int fill_stat_mr_entry(struct sk_buff *msg, bool has_cap_net_admin,
> +			      struct rdma_restrack_entry *res, uint32_t port)
> +{
> +	struct ib_mr *mr = container_of(res, struct ib_mr, res);
> +	struct ib_device *dev = mr->pd->device;
> +	struct ib_odp_counters odp_stats;
> +	struct nlattr *table_attr;
> +
> +	if (nla_put_u32(msg, RDMA_NLDEV_ATTR_RES_MRN, res->id))
> +		goto err;
> +
> +	if (!dev->ops.fill_odp_stats)
> +		return 0;
> +
> +	if (!dev->ops.fill_odp_stats(mr, &odp_stats))
> +		return 0;

As Parav says this seems to be wrong for !ODP MRs. Can we even detect
!ODP at this point?

> +
> +	table_attr = nla_nest_start(msg,
> +				    RDMA_NLDEV_ATTR_STAT_HWCOUNTERS);
> +
> +	if (!table_attr)
> +		return -EMSGSIZE;
> +
> +	if (fill_stat_hwcounter_entry(msg, "page_faults",
> +				      (u64)atomic64_read(&odp_stats.faults)))

Why the cast?

> +static bool mlx5_ib_fill_odp_stats(struct ib_mr *ibmr,
> +				   struct ib_odp_counters *cnt)
> +{
> +	struct mlx5_ib_mr *mr = to_mmr(ibmr);
> +
> +	if (!is_odp_mr(mr))
> +		return false;
> +
> +	memcpy(cnt, &to_ib_umem_odp(mr->umem)->odp_stats,
> +	       sizeof(struct ib_odp_counters));

Can't memcpy atomic64, have to open code a copy using atomic64_read.

> @@ -6316,6 +6331,7 @@ static const struct ib_device_ops mlx5_ib_dev_ops = {
>  	.get_dev_fw_str = get_dev_fw_str,
>  	.get_dma_mr = mlx5_ib_get_dma_mr,
>  	.get_link_layer = mlx5_ib_port_link_layer,
> +	.fill_odp_stats = mlx5_ib_fill_odp_stats,

Randomly again..

Jason