linux-kernel - Re: [PATCH v2 net-next 1/2] net-sysfs: display two backlog queue len separately

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Date:   Tue, 14 Mar 2023 12:37:45 +0100
From:   Simon Horman <simon.horman@...igine.com>
To:     Jason Xing <kerneljasonxing@...il.com>
Cc:     davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
        pabeni@...hat.com, ast@...nel.org, daniel@...earbox.net,
        hawk@...nel.org, john.fastabend@...il.com,
        stephen@...workplumber.org, sinquersw@...il.com,
        bpf@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, Jason Xing <kernelxing@...cent.com>
Subject: Re: [PATCH v2 net-next 1/2] net-sysfs: display two backlog queue len
 separately

On Tue, Mar 14, 2023 at 11:05:31AM +0800, Jason Xing wrote:
> From: Jason Xing <kernelxing@...cent.com>
> 
> Sometimes we need to know which one of backlog queue can be exactly
> long enough to cause some latency when debugging this part is needed.
> Thus, we can then separate the display of both.
> 
> Signed-off-by: Jason Xing <kernelxing@...cent.com>
> ---
> v2: keep the total len of backlog queues untouched as Eric said
> Link: https://lore.kernel.org/lkml/20230311151756.83302-1-kerneljasonxing@gmail.com/
> ---
>  net/core/net-procfs.c | 20 ++++++++++++++++----
>  1 file changed, 16 insertions(+), 4 deletions(-)
> 
> diff --git a/net/core/net-procfs.c b/net/core/net-procfs.c
> index 1ec23bf8b05c..2809b663e78d 100644
> --- a/net/core/net-procfs.c
> +++ b/net/core/net-procfs.c
> @@ -115,10 +115,19 @@ static int dev_seq_show(struct seq_file *seq, void *v)
>  	return 0;
>  }
>  
> +static u32 softnet_input_pkt_queue_len(struct softnet_data *sd)
> +{
> +	return skb_queue_len_lockless(&sd->input_pkt_queue);
> +}
> +
> +static u32 softnet_process_queue_len(struct softnet_data *sd)
> +{
> +	return skb_queue_len_lockless(&sd->process_queue);
> +}
> +
>  static u32 softnet_backlog_len(struct softnet_data *sd)
>  {
> -	return skb_queue_len_lockless(&sd->input_pkt_queue) +
> -	       skb_queue_len_lockless(&sd->process_queue);
> +	return softnet_input_pkt_queue_len(sd) + softnet_process_queue_len(sd);
>  }
>  
>  static struct softnet_data *softnet_get_online(loff_t *pos)
> @@ -169,12 +178,15 @@ static int softnet_seq_show(struct seq_file *seq, void *v)
>  	 * mapping the data a specific CPU
>  	 */
>  	seq_printf(seq,
> -		   "%08x %08x %08x %08x %08x %08x %08x %08x %08x %08x %08x %08x %08x\n",
> +		   "%08x %08x %08x %08x %08x %08x %08x %08x %08x %08x %08x %08x %08x "
> +		   "%08x %08x\n",
>  		   sd->processed, sd->dropped, sd->time_squeeze, 0,
>  		   0, 0, 0, 0, /* was fastroute */
>  		   0,	/* was cpu_collision */
>  		   sd->received_rps, flow_limit_count,
> -		   softnet_backlog_len(sd), (int)seq->index);
> +		   softnet_backlog_len(sd),	/* keep it untouched */

I'm not sure the comment on the line above buys
us much outside of the context of development of this patch.

Likewise in patch 2/2.

That not withstanding, this looks good to me.

Reviewed-by: Simon Horman <simon.horman@...igine.com>


> +		   (int)seq->index,
> +		   softnet_input_pkt_queue_len(sd), softnet_process_queue_len(sd));
>  	return 0;
>  }
>  
> -- 
> 2.37.3
>