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core: add stat to track unresolved discards in neighbor cache 

in __neigh_event_send, if we have a neighbour entry which is in
NUD_INCOMPLETE state, we enqueue any outbound frames to that neighbour
to the neighbours arp_queue, which is default capped to a length of 3
skbs.  If that queue exceeds its set length, it will drop an skb on
the queue to enqueue the newly arrived skb.  This results in a drop
for which we have no statistics incremented.  This patch adds an
unresolved_discards stat to /proc/net/stat/ndisc_cache to track these
lost frames.

Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Neil Horman 2008-07-16 20:50:49 -07:00 committed by David S. Miller
parent ed88098e25
commit 9a6d276e85
2 changed files with 8 additions and 4 deletions
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4
include/net/neighbour.h
View File

@ -75,7 +75,7 @@ struct neigh_statistics
unsigned long destroys; /* number of destroyed neighs */
unsigned long hash_grows; /* number of hash resizes */
unsigned long res_failed; /* nomber of failed resolutions */
unsigned long res_failed; /* number of failed resolutions */
unsigned long lookups; /* number of lookups */
unsigned long hits; /* number of hits (among lookups) */
@ -85,6 +85,8 @@ struct neigh_statistics
unsigned long periodic_gc_runs; /* number of periodic GC runs */
unsigned long forced_gc_runs; /* number of forced GC runs */
unsigned long unres_discards; /* number of unresolved drops */
};
#define NEIGH_CACHE_STAT_INC(tbl, field) \

8
net/core/neighbour.c
View File

@ -930,6 +930,7 @@ int __neigh_event_send(struct neighbour *neigh, struct sk_buff *skb)
buff = neigh->arp_queue.next;
__skb_unlink(buff, &neigh->arp_queue);
kfree_skb(buff);
NEIGH_CACHE_STAT_INC(neigh->tbl, unres_discards);
}
__skb_queue_tail(&neigh->arp_queue, skb);
}
@ -2462,12 +2463,12 @@ static int neigh_stat_seq_show(struct seq_file *seq, void *v)
struct neigh_statistics *st = v;
if (v == SEQ_START_TOKEN) {
seq_printf(seq, "entries allocs destroys hash_grows lookups hits res_failed rcv_probes_mcast rcv_probes_ucast periodic_gc_runs forced_gc_runs\n");
seq_printf(seq, "entries allocs destroys hash_grows lookups hits res_failed rcv_probes_mcast rcv_probes_ucast periodic_gc_runs forced_gc_runs unresolved_discards\n");
return 0;
}
seq_printf(seq, "%08x %08lx %08lx %08lx %08lx %08lx %08lx "
"%08lx %08lx %08lx %08lx\n",
"%08lx %08lx %08lx %08lx %08lx\n",
atomic_read(&tbl->entries),
st->allocs,
@ -2483,7 +2484,8 @@ static int neigh_stat_seq_show(struct seq_file *seq, void *v)
st->rcv_probes_ucast,
st->periodic_gc_runs,
st->forced_gc_runs
st->forced_gc_runs,
st->unres_discards
);
return 0;