[Intel-wired-lan] [PATCH S23 14/15] ice: Use smaller sized integer types

[Kaminski, Pawel]

Dear Paul,

thank you for your comment.

Indeed part of the intention was to denote that those are/should be unsigned values.
Another thing was to keep up with the types of variables those values come from.

I have to agree with you comment assuming this may use more memory than standard unsigned int.

To be perfectly honest I did not know that u16 will result in worse memory usage than uint.

Regards,
PK

-----Original Message-----
From: Paul Menzel [mailto:pmenzel at molgen.mpg.de] 
Sent: Friday, June 28, 2019 8:49 AM
To: Nguyen, Anthony L <anthony.l.nguyen at intel.com>; Kaminski, Pawel <pawel.kaminski at intel.com>
Cc: intel-wired-lan at lists.osuosl.org
Subject: Re: [Intel-wired-lan] [PATCH S23 14/15] ice: Use smaller sized integer types

Dear Tony, dear Pawel,


On 6/27/19 4:41 PM, Tony Nguyen wrote:
> From: Pawel Kaminski <pawel.kaminski at intel.com>
> 
> The max number queues supported by the device is 768; we only need
> a u16 to represent this.

What is the benefit of this? It won’t make any difference in the
generated code to my knowledge [1].

Maybe just use unsigned int, if you want to denote that negative
numbers are not allowed?

> Signed-off-by: Pawel Kaminski <pawel.kaminski at intel.com>
> ---
>  drivers/net/ethernet/intel/ice/ice_virtchnl_pf.c | 14 +++++++-------
>  1 file changed, 7 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/net/ethernet/intel/ice/ice_virtchnl_pf.c b/drivers/net/ethernet/intel/ice/ice_virtchnl_pf.c
> index f2ebbe83ae4c..72a9e79dd76d 100644
> --- a/drivers/net/ethernet/intel/ice/ice_virtchnl_pf.c
> +++ b/drivers/net/ethernet/intel/ice/ice_virtchnl_pf.c
> @@ -2339,11 +2339,11 @@ static int ice_vc_request_qs_msg(struct ice_vf *vf, u8 *msg)
>  	enum virtchnl_status_code v_ret = VIRTCHNL_STATUS_SUCCESS;
>  	struct virtchnl_vf_res_request *vfres =
>  		(struct virtchnl_vf_res_request *)msg;
> -	int req_queues = vfres->num_queue_pairs;
> +	u16 req_queues = vfres->num_queue_pairs;
>  	struct ice_pf *pf = vf->pf;
> -	int max_allowed_vf_queues;
> -	int tx_rx_queue_left;
> -	int cur_queues;
> +	u16 max_allowed_vf_queues;
> +	u16 tx_rx_queue_left;
> +	u16 cur_queues;
>  
>  	if (!test_bit(ICE_VF_STATE_ACTIVE, vf->vf_states)) {
>  		v_ret = VIRTCHNL_STATUS_ERR_PARAM;
> @@ -2353,10 +2353,10 @@ static int ice_vc_request_qs_msg(struct ice_vf *vf, u8 *msg)
>  	cur_queues = vf->num_vf_qs;
>  	tx_rx_queue_left = min_t(int, pf->q_left_tx, pf->q_left_rx);
>  	max_allowed_vf_queues = tx_rx_queue_left + cur_queues;
> -	if (req_queues <= 0) {
> +	if (!req_queues) {
>  		dev_err(&pf->pdev->dev,
> -			"VF %d tried to request %d queues. Ignoring.\n",
> -			vf->vf_id, req_queues);
> +			"VF %d tried to request 0 queues. Ignoring.\n",
> +			vf->vf_id);
>  	} else if (req_queues > ICE_MAX_BASE_QS_PER_VF) {
>  		dev_err(&pf->pdev->dev,
>  			"VF %d tried to request more than %d queues.\n",


Kind regards,

Paul


[1]: http://notabs.org/coding/smallIntsBigPenalty.htm