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net-sysfs: add backlog len and CPU id to softnet data

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Currently the backlog status in not exposed to user-space.
Since long backlogs (or simply not empty ones) can be a
source of noticeable latency, -RT deployments need some way
to inspect it.

Additionally, there isn't a direct match between 'softnet_stat'
lines and the related CPU - sd for offline CPUs are not dumped -
so this patch also includes the CPU id into such entry.

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Paolo Abeni 2020-09-18 18:00:46 +02:00 committed by David S. Miller
parent c4f084edd3
commit 7d58e65558
1 changed files with 13 additions and 2 deletions
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15
net/core/net-procfs.c
View file

@ -116,6 +116,12 @@ static int dev_seq_show(struct seq_file *seq, void *v)
return 0;
}
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);
}
static struct softnet_data *softnet_get_online(loff_t *pos)
{
struct softnet_data *sd = NULL;
@ -159,12 +165,17 @@ static int softnet_seq_show(struct seq_file *seq, void *v)
rcu_read_unlock();
#endif
/* the index is the CPU id owing this sd. Since offline CPUs are not
* displayed, it would be othrwise not trivial for the user-space
* mapping the data a specific CPU
*/
seq_printf(seq,
"%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\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);
sd->received_rps, flow_limit_count,
softnet_backlog_len(sd), (int)seq->index);
return 0;
}