netdev - Re: [PATCH v4 net-next 1/2] net-sysfs: display two backlog queue len separately

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Date:   Sun, 19 Mar 2023 11:05:57 +0800
From:   Jason Xing <kerneljasonxing@...il.com>
To:     jbrouer@...hat.com, 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, simon.horman@...igine.com,
        sinquersw@...il.com
Cc:     bpf@...r.kernel.org, netdev@...r.kernel.org,
        Jason Xing <kernelxing@...cent.com>
Subject: Re: [PATCH v4 net-next 1/2] net-sysfs: display two backlog queue len separately

On Wed, Mar 15, 2023 at 5:21 PM Jason Xing <kerneljasonxing@...il.com> 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>
> Reviewed-by: Simon Horman <simon.horman@...igine.com>

I just noticed that the state of this patch is "Changes Requested" in
the patchwork[1]. But I didn't see any feedback on this. Please let me
know if someone is available and provide more suggestions which are
appreciated.

[1]: https://patchwork.kernel.org/project/netdevbpf/patch/20230315092041.35482-2-kerneljasonxing@gmail.com/

Thanks,
Jason

> ---
> v4:
> 1) avoid the inconsistency through caching variables suggested
> by Eric.
> Link: https://lore.kernel.org/lkml/20230314030532.9238-2-kerneljasonxing@gmail.com/
> 2) remove the unused function: softnet_backlog_len()
>
> v3: drop the comment suggested by Simon
> Link: https://lore.kernel.org/lkml/20230314030532.9238-2-kerneljasonxing@gmail.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 | 18 +++++++++++++-----
>  1 file changed, 13 insertions(+), 5 deletions(-)
>
> diff --git a/net/core/net-procfs.c b/net/core/net-procfs.c
> index 1ec23bf8b05c..09f7ed1a04e8 100644
> --- a/net/core/net-procfs.c
> +++ b/net/core/net-procfs.c
> @@ -115,10 +115,14 @@ static int dev_seq_show(struct seq_file *seq, void *v)
>         return 0;
>  }
>
> -static u32 softnet_backlog_len(struct softnet_data *sd)
> +static u32 softnet_input_pkt_queue_len(struct softnet_data *sd)
>  {
> -       return skb_queue_len_lockless(&sd->input_pkt_queue) +
> -              skb_queue_len_lockless(&sd->process_queue);
> +       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 struct softnet_data *softnet_get_online(loff_t *pos)
> @@ -152,6 +156,8 @@ static void softnet_seq_stop(struct seq_file *seq, void *v)
>  static int softnet_seq_show(struct seq_file *seq, void *v)
>  {
>         struct softnet_data *sd = v;
> +       u32 input_qlen = softnet_input_pkt_queue_len(sd);
> +       u32 process_qlen = softnet_process_queue_len(sd);
>         unsigned int flow_limit_count = 0;
>
>  #ifdef CONFIG_NET_FLOW_LIMIT
> @@ -169,12 +175,14 @@ 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);
> +                  input_qlen + process_qlen, (int)seq->index,
> +                  input_qlen, process_qlen);
>         return 0;
>  }
>
> --
> 2.37.3
>