linux-kernel - Re: [Intel-wired-lan] [PATCH V2 net] ice: Re-organizes reqstd/avail {R, T}XQ check/code for efficiency+readability

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Message-ID: <7974e665-73bd-401c-f023-9da568e1dffc@molgen.mpg.de>
Date:   Wed, 21 Apr 2021 07:35:43 +0200
From:   Paul Menzel <pmenzel@...gen.mpg.de>
To:     Salil Mehta <salil.mehta@...wei.com>
Cc:     linuxarm@...neuler.org, netdev@...r.kernel.org,
        linuxarm@...wei.com, linux-kernel@...r.kernel.org,
        Jeff Kirsher <jeffrey.t.kirsher@...el.com>,
        intel-wired-lan@...ts.osuosl.org,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>
Subject: Re: [Intel-wired-lan] [PATCH V2 net] ice: Re-organizes reqstd/avail
 {R, T}XQ check/code for efficiency+readability

Dear Salil,


Thank you very much for your patch.

In the git commit message summary, could you please use imperative mood [1]?

> Re-organize reqstd/avail {R, T}XQ check/code for efficiency+readability

It’s a bit long though. Maybe:

> Avoid unnecessary assignment with user specified {R,T}XQs

Am 14.04.21 um 00:44 schrieb Salil Mehta:
> If user has explicitly requested the number of {R,T}XQs, then it is
> unnecessary to get the count of already available {R,T}XQs from the
> PF avail_{r,t}xqs bitmap. This value will get overridden by user specified
> value in any case.
> 
> This patch does minor re-organization of the code for improving the flow
> and readabiltiy. This scope of improvement was found during the review of

readabil*it*y

> the ICE driver code.
> 
> FYI, I could not test this change due to unavailability of the hardware.
> It would be helpful if somebody can test this patch and provide Tested-by
> Tag. Many thanks!

This should go outside the commit message (below the --- for example).

> Fixes: 87324e747fde ("ice: Implement ethtool ops for channels")

Did you check the behavior before is actually a bug? Or is it just for 
the detection heuristic for commits to be applied to the stable series?

> Cc: intel-wired-lan@...ts.osuosl.org
> Cc: Jeff Kirsher <jeffrey.t.kirsher@...el.com>
> Signed-off-by: Salil Mehta <salil.mehta@...wei.com>
> --
> Change V1->V2
>   (*) Fixed the comments from Anthony Nguyen(Intel)
>       Link: https://lkml.org/lkml/2021/4/12/1997
> ---
>   drivers/net/ethernet/intel/ice/ice_lib.c | 14 ++++++++------
>   1 file changed, 8 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/net/ethernet/intel/ice/ice_lib.c b/drivers/net/ethernet/intel/ice/ice_lib.c
> index d13c7fc8fb0a..d77133d6baa7 100644
> --- a/drivers/net/ethernet/intel/ice/ice_lib.c
> +++ b/drivers/net/ethernet/intel/ice/ice_lib.c
> @@ -161,12 +161,13 @@ static void ice_vsi_set_num_qs(struct ice_vsi *vsi, u16 vf_id)
>   
>   	switch (vsi->type) {
>   	case ICE_VSI_PF:
> -		vsi->alloc_txq = min3(pf->num_lan_msix,
> -				      ice_get_avail_txq_count(pf),
> -				      (u16)num_online_cpus());
>   		if (vsi->req_txq) {
>   			vsi->alloc_txq = vsi->req_txq;
>   			vsi->num_txq = vsi->req_txq;
> +		} else {
> +			vsi->alloc_txq = min3(pf->num_lan_msix,
> +					      ice_get_avail_txq_count(pf),
> +					      (u16)num_online_cpus());
>   		}

I am curious, did you check the compiler actually creates different 
code, or did it notice the inefficiency by itself and optimized it already?

>   
>   		pf->num_lan_tx = vsi->alloc_txq;
> @@ -175,12 +176,13 @@ static void ice_vsi_set_num_qs(struct ice_vsi *vsi, u16 vf_id)
>   		if (!test_bit(ICE_FLAG_RSS_ENA, pf->flags)) {
>   			vsi->alloc_rxq = 1;
>   		} else {
> -			vsi->alloc_rxq = min3(pf->num_lan_msix,
> -					      ice_get_avail_rxq_count(pf),
> -					      (u16)num_online_cpus());
>   			if (vsi->req_rxq) {
>   				vsi->alloc_rxq = vsi->req_rxq;
>   				vsi->num_rxq = vsi->req_rxq;
> +			} else {
> +				vsi->alloc_rxq = min3(pf->num_lan_msix,
> +						      ice_get_avail_rxq_count(pf),
> +						      (u16)num_online_cpus());
>   			}
>   		}
>   


Kind regards,

Paul