diff mbox series

[v2,net-next,1/2] net-sysfs: display two backlog queue len separately

Message ID 20230314030532.9238-2-kerneljasonxing@gmail.com
State New
Headers
Series add some detailed data when reading softnet_stat |

Commit Message

Jason Xing March 14, 2023, 3:05 a.m. UTC 
  From: Jason Xing <kernelxing@tencent.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@tencent.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(-)

Comments

Simon Horman March 14, 2023, 11:37 a.m. UTC | #1 
On Tue, Mar 14, 2023 at 11:05:31AM +0800, Jason Xing wrote:
> From: Jason Xing <kernelxing@tencent.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@tencent.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@corigine.com>


> +		   (int)seq->index,
> +		   softnet_input_pkt_queue_len(sd), softnet_process_queue_len(sd));
>  	return 0;
>  }
>  
> -- 
> 2.37.3
>
Eric Dumazet March 14, 2023, 2:59 p.m. UTC | #2 
On Mon, Mar 13, 2023 at 8:06 PM Jason Xing <kerneljasonxing@gmail.com> wrote:
>
> From: Jason Xing <kernelxing@tencent.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@tencent.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);

Reading these variables twice might lead to inconsistency that can
easily be avoided.

I would suggest you cache the values,

u32 len1 = softnet_input_pkt_queue_len(sd);
u32 len2 = 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 */
                    len1 + len2.

> +                  (int)seq->index,
> +                  softnet_input_pkt_queue_len(sd), softnet_process_queue_len(sd));
               len1,  len2);

>         return 0;
>  }
>
> --
> 2.37.3
>
Jason Xing March 14, 2023, 3:44 p.m. UTC | #3 
On Tue, Mar 14, 2023 at 10:59 PM Eric Dumazet <edumazet@google.com> wrote:
>
> On Mon, Mar 13, 2023 at 8:06 PM Jason Xing <kerneljasonxing@gmail.com> wrote:
> >
> > From: Jason Xing <kernelxing@tencent.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@tencent.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);
>
[...]
> Reading these variables twice might lead to inconsistency that can
> easily be avoided.
>
> I would suggest you cache the values,
>
> u32 len1 = softnet_input_pkt_queue_len(sd);
> u32 len2 = softnet_process_queue_len(sd);

Agreed. Thank you, Eric. I should have realized that.

Also, the 2/2 patch which is all about the time_/budget_squeeze should
avoid such inconsistency, I think.

Jason
>
>
>
> >  }
> >
> >  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 */
>                     len1 + len2.
>
> > +                  (int)seq->index,
> > +                  softnet_input_pkt_queue_len(sd), softnet_process_queue_len(sd));
>                len1,  len2);
>
> >         return 0;
> >  }
> >
> > --
> > 2.37.3
> >
diff mbox series

Patch

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