Subject: [PATCH net-next] net: netdev_pick_tx: use get_xps_q if xps map is set

From: "govindarajulu.v" <[email protected]>

netdev_pick_tx ignores the xps map configuration if netdev->ndo_select_queue
is defined. Most of the drivers define ndo_select_queue. The problem with this
is, if admin wants kernel to pick tx queue based on xps map (instead of driver
defined ndo_select_queue), he has to netdev->ndo_select_queue = NULL, compile
and reload.

This patch fixes it by checking if dev->xps_maps is defined. If yes it
proceeds with get_xps_queue. If not it proceeds with netdev->ndo_select_queue
(if defined).

Compile test only.

Signed-off-by: govindarajulu.v <[email protected]>
---
net/core/flow_dissector.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
index 00ee068..b2e3c81 100644
--- a/net/core/flow_dissector.c
+++ b/net/core/flow_dissector.c
@@ -368,10 +368,11 @@ struct netdev_queue *netdev_pick_tx(struct net_device *dev,

if (dev->real_num_tx_queues != 1) {
const struct net_device_ops *ops = dev->netdev_ops;
- if (ops->ndo_select_queue)
- queue_index = ops->ndo_select_queue(dev, skb);
- else
+ if (rcu_access_pointer(dev->xps_maps) ||
+ !ops->ndo_select_queue)
queue_index = __netdev_pick_tx(dev, skb);
+ else
+ queue_index = ops->ndo_select_queue(dev, skb);
queue_index = dev_cap_txqueue(dev, queue_index);
}

--
1.8.2.3


2013-05-17 13:35:39

by Eric Dumazet

[permalink] [raw]
Subject: Re: [PATCH net-next] net: netdev_pick_tx: use get_xps_q if xps map is set

On Fri, 2013-05-17 at 14:18 +0530, govindarajulu.v wrote:
> From: "govindarajulu.v" <[email protected]>
>
> netdev_pick_tx ignores the xps map configuration if netdev->ndo_select_queue
> is defined. Most of the drivers define ndo_select_queue. The problem with this
> is, if admin wants kernel to pick tx queue based on xps map (instead of driver
> defined ndo_select_queue), he has to netdev->ndo_select_queue = NULL, compile
> and reload.
>
> This patch fixes it by checking if dev->xps_maps is defined. If yes it
> proceeds with get_xps_queue. If not it proceeds with netdev->ndo_select_queue
> (if defined).
>
> Compile test only.

I do not think its right, take a look at
drivers/net/ethernet/intel/ixgbe/ixgbe_main.c , around line 6467


Subject: Re: [PATCH net-next] net: netdev_pick_tx: use get_xps_q if xps map is set

On 05/17/2013 07:05 PM, Eric Dumazet wrote:
> On Fri, 2013-05-17 at 14:18 +0530, govindarajulu.v wrote:
>> From: "govindarajulu.v" <[email protected]>
>>
>> netdev_pick_tx ignores the xps map configuration if netdev->ndo_select_queue
>> is defined. Most of the drivers define ndo_select_queue. The problem with this
>> is, if admin wants kernel to pick tx queue based on xps map (instead of driver
>> defined ndo_select_queue), he has to netdev->ndo_select_queue = NULL, compile
>> and reload.
>>
>> This patch fixes it by checking if dev->xps_maps is defined. If yes it
>> proceeds with get_xps_queue. If not it proceeds with netdev->ndo_select_queue
>> (if defined).
>>
>> Compile test only.
>
> I do not think its right, take a look at
> drivers/net/ethernet/intel/ixgbe/ixgbe_main.c , around line 6467

I see. In ixgbe_select_queue we use __netdev_pick_tx only if packet is not
FCOE & FIP.

If you see
bnx2x_select_queue in drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c, line 1832
and mlx4_en_select_queue in drivers/net/ethernet/mellanox/mlx4/en_tx.c, line 547.
we cannot have xps working with these drivers.

This needs to be fixed by replacing __skb_tx_hash with __netdev_pick_tx. Am i
correct?

thanks
//govind

2013-05-17 22:03:24

by Eric Dumazet

[permalink] [raw]
Subject: Re: [PATCH net-next] net: netdev_pick_tx: use get_xps_q if xps map is set

On Sat, 2013-05-18 at 01:20 +0530, govind wrote:

> I see. In ixgbe_select_queue we use __netdev_pick_tx only if packet is not
> FCOE & FIP.
>
> If you see
> bnx2x_select_queue in drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c, line 1832
> and mlx4_en_select_queue in drivers/net/ethernet/mellanox/mlx4/en_tx.c, line 547.
> we cannot have xps working with these drivers.
>
> This needs to be fixed by replacing __skb_tx_hash with __netdev_pick_tx. Am i
> correct?

Yes, this seems better.

Subject: Re: [PATCH net-next] net: netdev_pick_tx: use get_xps_q if xps map is set

>On 05/18/2013 03:33 AM, Eric Dumazet wrote:
> On Sat, 2013-05-18 at 01:20 +0530, govind wrote:
>
>> I see. In ixgbe_select_queue we use __netdev_pick_tx only if packet is not
>> FCOE & FIP.
>>
>> If you see
>> bnx2x_select_queue in drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c, line 1832
>> and mlx4_en_select_queue in drivers/net/ethernet/mellanox/mlx4/en_tx.c, line 547.
>> we cannot have xps working with these drivers.
>>
>> This needs to be fixed by replacing __skb_tx_hash with __netdev_pick_tx. Am i
>> correct?
>
> Yes, this seems better.

thanks eric, i will send patch soon.

//govind