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fib_trie: Update usage stats to be percpu instead of global variables

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The trie usage stats were currently being shared by all threads that were
calling fib_table_lookup.  As a result when multiple threads were
performing lookups simultaneously the trie would begin to cache bounce
between those threads.

In order to prevent this I have updated the usage stats to use a set of
percpu variables.  By doing this we should be able to avoid the cache
bouncing and still make use of these stats.

Signed-off-by: Alexander Duyck <alexander.h.duyck@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Alexander Duyck 2014-12-31 10:55:29 -08:00 committed by David S. Miller
parent bec94d430f
commit 8274a97aa4
2 changed files with 49 additions and 21 deletions
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2
net/ipv4/fib_frontend.c
View File

@ -67,7 +67,7 @@ static int __net_init fib4_rules_init(struct net *net)
return 0;
fail:
kfree(local_table);
fib_free_table(local_table);
return -ENOMEM;
}
#else

68
net/ipv4/fib_trie.c
View File

@ -153,7 +153,7 @@ struct trie_stat {
struct trie {
struct rt_trie_node __rcu *trie;
#ifdef CONFIG_IP_FIB_TRIE_STATS
struct trie_use_stats stats;
struct trie_use_stats __percpu *stats;
#endif
};
@ -631,7 +631,7 @@ static struct rt_trie_node *resize(struct trie *t, struct tnode *tn)
if (IS_ERR(tn)) {
tn = old_tn;
#ifdef CONFIG_IP_FIB_TRIE_STATS
t->stats.resize_node_skipped++;
this_cpu_inc(t->stats->resize_node_skipped);
#endif
break;
}
@ -658,7 +658,7 @@ static struct rt_trie_node *resize(struct trie *t, struct tnode *tn)
if (IS_ERR(tn)) {
tn = old_tn;
#ifdef CONFIG_IP_FIB_TRIE_STATS
t->stats.resize_node_skipped++;
this_cpu_inc(t->stats->resize_node_skipped);
#endif
break;
}
@ -1357,7 +1357,7 @@ static int check_leaf(struct fib_table *tb, struct trie *t, struct leaf *l,
err = fib_props[fa->fa_type].error;
if (err) {
#ifdef CONFIG_IP_FIB_TRIE_STATS
t->stats.semantic_match_passed++;
this_cpu_inc(t->stats->semantic_match_passed);
#endif
return err;
}
@ -1372,7 +1372,7 @@ static int check_leaf(struct fib_table *tb, struct trie *t, struct leaf *l,
continue;
#ifdef CONFIG_IP_FIB_TRIE_STATS
t->stats.semantic_match_passed++;
this_cpu_inc(t->stats->semantic_match_passed);
#endif
res->prefixlen = li->plen;
res->nh_sel = nhsel;
@ -1388,7 +1388,7 @@ static int check_leaf(struct fib_table *tb, struct trie *t, struct leaf *l,
}
#ifdef CONFIG_IP_FIB_TRIE_STATS
t->stats.semantic_match_miss++;
this_cpu_inc(t->stats->semantic_match_miss);
#endif
}
@ -1399,6 +1399,9 @@ int fib_table_lookup(struct fib_table *tb, const struct flowi4 *flp,
struct fib_result *res, int fib_flags)
{
struct trie *t = (struct trie *) tb->tb_data;
#ifdef CONFIG_IP_FIB_TRIE_STATS
struct trie_use_stats __percpu *stats = t->stats;
#endif
int ret;
struct rt_trie_node *n;
struct tnode *pn;
@ -1417,7 +1420,7 @@ int fib_table_lookup(struct fib_table *tb, const struct flowi4 *flp,
goto failed;
#ifdef CONFIG_IP_FIB_TRIE_STATS
t->stats.gets++;
this_cpu_inc(stats->gets);
#endif
/* Just a leaf? */
@ -1441,7 +1444,7 @@ int fib_table_lookup(struct fib_table *tb, const struct flowi4 *flp,
if (n == NULL) {
#ifdef CONFIG_IP_FIB_TRIE_STATS
t->stats.null_node_hit++;
this_cpu_inc(stats->null_node_hit);
#endif
goto backtrace;
}
@ -1576,7 +1579,7 @@ backtrace:
chopped_off = 0;
#ifdef CONFIG_IP_FIB_TRIE_STATS
t->stats.backtrack++;
this_cpu_inc(stats->backtrack);
#endif
goto backtrace;
}
@ -1830,6 +1833,11 @@ int fib_table_flush(struct fib_table *tb)
void fib_free_table(struct fib_table *tb)
{
#ifdef CONFIG_IP_FIB_TRIE_STATS
struct trie *t = (struct trie *)tb->tb_data;
free_percpu(t->stats);
#endif /* CONFIG_IP_FIB_TRIE_STATS */
kfree(tb);
}
@ -1973,7 +1981,14 @@ struct fib_table *fib_trie_table(u32 id)
tb->tb_num_default = 0;
t = (struct trie *) tb->tb_data;
memset(t, 0, sizeof(*t));
RCU_INIT_POINTER(t->trie, NULL);
#ifdef CONFIG_IP_FIB_TRIE_STATS
t->stats = alloc_percpu(struct trie_use_stats);
if (!t->stats) {
kfree(tb);
tb = NULL;
}
#endif
return tb;
}
@ -2139,18 +2154,31 @@ static void trie_show_stats(struct seq_file *seq, struct trie_stat *stat)
#ifdef CONFIG_IP_FIB_TRIE_STATS
static void trie_show_usage(struct seq_file *seq,
const struct trie_use_stats *stats)
const struct trie_use_stats __percpu *stats)
{
struct trie_use_stats s = { 0 };
int cpu;
/* loop through all of the CPUs and gather up the stats */
for_each_possible_cpu(cpu) {
const struct trie_use_stats *pcpu = per_cpu_ptr(stats, cpu);
s.gets += pcpu->gets;
s.backtrack += pcpu->backtrack;
s.semantic_match_passed += pcpu->semantic_match_passed;
s.semantic_match_miss += pcpu->semantic_match_miss;
s.null_node_hit += pcpu->null_node_hit;
s.resize_node_skipped += pcpu->resize_node_skipped;
}
seq_printf(seq, "\nCounters:\n---------\n");
seq_printf(seq, "gets = %u\n", stats->gets);
seq_printf(seq, "backtracks = %u\n", stats->backtrack);
seq_printf(seq, "gets = %u\n", s.gets);
seq_printf(seq, "backtracks = %u\n", s.backtrack);
seq_printf(seq, "semantic match passed = %u\n",
stats->semantic_match_passed);
seq_printf(seq, "semantic match miss = %u\n",
stats->semantic_match_miss);
seq_printf(seq, "null node hit= %u\n", stats->null_node_hit);
seq_printf(seq, "skipped node resize = %u\n\n",
stats->resize_node_skipped);
s.semantic_match_passed);
seq_printf(seq, "semantic match miss = %u\n", s.semantic_match_miss);
seq_printf(seq, "null node hit= %u\n", s.null_node_hit);
seq_printf(seq, "skipped node resize = %u\n\n", s.resize_node_skipped);
}
#endif /* CONFIG_IP_FIB_TRIE_STATS */
@ -2191,7 +2219,7 @@ static int fib_triestat_seq_show(struct seq_file *seq, void *v)
trie_collect_stats(t, &stat);
trie_show_stats(seq, &stat);
#ifdef CONFIG_IP_FIB_TRIE_STATS
trie_show_usage(seq, &t->stats);
trie_show_usage(seq, t->stats);
#endif
}
}