netdev - RE: [RFC 4/5] i40e/ethtool: support coalesce getting by queue

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Message-ID: <FC41C24E35F18A40888AACA1A36F3E418AFD1C84@fmsmsx115.amr.corp.intel.com>
Date:	Thu, 17 Dec 2015 22:43:52 +0000
From:	"Nelson, Shannon" <shannon.nelson@...el.com>
To:	"Liang, Kan" <kan.liang@...el.com>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"davem@...emloft.net" <davem@...emloft.net>,
	"bwh@...nel.org" <bwh@...nel.org>
CC:	"Brandeburg, Jesse" <jesse.brandeburg@...el.com>,
	"andi@...stfloor.org" <andi@...stfloor.org>,
	"f.fainelli@...il.com" <f.fainelli@...il.com>,
	"alexander.duyck@...il.com" <alexander.duyck@...il.com>,
	"Kirsher, Jeffrey T" <jeffrey.t.kirsher@...el.com>,
	"Wyborny, Carolyn" <carolyn.wyborny@...el.com>,
	"Skidmore, Donald C" <donald.c.skidmore@...el.com>,
	"Williams, Mitch A" <mitch.a.williams@...el.com>,
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Subject: RE: [RFC 4/5] i40e/ethtool: support coalesce getting by queue

> From: Kan Liang <kan.liang@...el.com>
> 
> This patch implements get_per_queue_coalesce for i40e driver.
> For i40e driver, only rx and tx usecs has per queue value. So only these
> two parameters are read from specific registers. For other interrupt
> coalescing parameters, they are shared among queues. The values which
> are stored in vsi will be return.
> 
> Signed-off-by: Kan Liang <kan.liang@...el.com>
> ---
>  drivers/net/ethernet/intel/i40e/i40e_ethtool.c | 34
> ++++++++++++++++++++++++--
>  1 file changed, 32 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/net/ethernet/intel/i40e/i40e_ethtool.c
> b/drivers/net/ethernet/intel/i40e/i40e_ethtool.c
> index 3f385ff..b41f0be 100644
> --- a/drivers/net/ethernet/intel/i40e/i40e_ethtool.c
> +++ b/drivers/net/ethernet/intel/i40e/i40e_ethtool.c
> @@ -1843,11 +1843,16 @@ static int i40e_set_phys_id(struct net_device
> *netdev,
>   * 125us (8000 interrupts per second) == ITR(62)
>   */
> 
> -static int i40e_get_coalesce(struct net_device *netdev,
> -			     struct ethtool_coalesce *ec)
> +static int __i40e_get_coalesce(struct net_device *netdev,
> +			       struct ethtool_coalesce *ec,
> +			       int queue)
>  {
>  	struct i40e_netdev_priv *np = netdev_priv(netdev);
>  	struct i40e_vsi *vsi = np->vsi;
> +	struct i40e_pf *pf = vsi->back;
> +	struct i40e_hw *hw = &pf->hw;
> +	struct i40e_q_vector *q_vector;
> +	u16 vector;
> 
>  	ec->tx_max_coalesced_frames_irq = vsi->work_limit;
>  	ec->rx_max_coalesced_frames_irq = vsi->work_limit;
> @@ -1869,9 +1874,33 @@ static int i40e_get_coalesce(struct net_device
> *netdev,
>  	ec->rx_coalesce_usecs_high = vsi->int_rate_limit;
>  	ec->tx_coalesce_usecs_high = vsi->int_rate_limit;
> 
> +	if (queue > 0) {
> +		if (queue >= vsi->num_q_vectors) {
> +			netif_info(pf, drv, netdev, "Invalid queue number\n");
> +			return -EINVAL;
> +		}
> +
> +		q_vector = vsi->q_vectors[queue];

The problem here is that there can be more queues than vectors and they're not spread round-robin style.  For example, if the VSI was only given 4 vectors, but has 8 queues, there will be 2 queues per vector paired up such that V0 <= {Q0, Q1}, V1 <= {Q2, Q3} ...

You'll need to check the requested queue number against vsi->num_queue_pairs for the max queue check, then look at vsi->tx_rings[queue].q_vector and/or vsi->rx_rings[queue].q_vector to find the actual q_vector for the requested queue.

sln

> +		vector = vsi->base_vector + queue;
> +
> +		ec->rx_coalesce_usecs = ITR_REG_TO_USEC(rd32(hw,
> I40E_PFINT_ITRN(0, vector - 1)));
> +		ec->tx_coalesce_usecs = ITR_REG_TO_USEC(rd32(hw,
> I40E_PFINT_ITRN(1, vector - 1)));
> +	}
>  	return 0;
>  }
> 
> +static int i40e_get_coalesce(struct net_device *netdev,
> +			     struct ethtool_coalesce *ec)
> +{
> +	return __i40e_get_coalesce(netdev, ec, -1);
> +}
> +
> +static int i40e_get_per_queue_coalesce(struct net_device *netdev, int
> queue,
> +				       struct ethtool_coalesce *ec)
> +{
> +	return __i40e_get_coalesce(netdev, ec, queue);
> +}
> +
>  static int i40e_set_coalesce(struct net_device *netdev,
>  			     struct ethtool_coalesce *ec)
>  {
> @@ -2788,6 +2817,7 @@ static const struct ethtool_ops i40e_ethtool_ops = {
>  	.get_ts_info		= i40e_get_ts_info,
>  	.get_priv_flags		= i40e_get_priv_flags,
>  	.set_priv_flags		= i40e_set_priv_flags,
> +	.get_per_queue_coalesce	= i40e_get_per_queue_coalesce,
>  };
> 
>  void i40e_set_ethtool_ops(struct net_device *netdev)
> --
> 1.7.11.7

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