Reading is very slow because ->start() performs a linear re-scan of the entire hash table until it finds the successor to the last dumped element. The current implementation uses 'pos' as the 'number of elements to skip, then does linear iteration until it has skipped 'pos' entries. Store the last bucket and the number of elements to skip in that bucket instead, so we can resume from bucket b directly. before this patch, its possible to read ~35k entries in one second, but each read() gets slower as the number of entries to skip grows: time timeout 60 cat /proc/net/ip_vs_conn > /tmp/all; wc -l /tmp/all real 1m0.007s user 0m0.003s sys 0m59.956s 140386 /tmp/all Only ~100k more got read in remaining the remaining 59s, and did not get nowhere near the 1m entries that are stored at the time. after this patch, dump completes very quickly: time cat /proc/net/ip_vs_conn > /tmp/all; wc -l /tmp/all real 0m2.286s user 0m0.004s sys 0m2.281s 1000001 /tmp/all Signed-off-by: Florian Westphal <fw@xxxxxxxxx> --- net/netfilter/ipvs/ip_vs_conn.c | 50 ++++++++++++++++++--------------- 1 file changed, 28 insertions(+), 22 deletions(-) diff --git a/net/netfilter/ipvs/ip_vs_conn.c b/net/netfilter/ipvs/ip_vs_conn.c index 7aba4760bbff..73f3dac159bb 100644 --- a/net/netfilter/ipvs/ip_vs_conn.c +++ b/net/netfilter/ipvs/ip_vs_conn.c @@ -1046,28 +1046,35 @@ ip_vs_conn_new(const struct ip_vs_conn_param *p, int dest_af, #ifdef CONFIG_PROC_FS struct ip_vs_iter_state { struct seq_net_private p; - struct hlist_head *l; + unsigned int bucket; + unsigned int skip_elems; }; -static void *ip_vs_conn_array(struct seq_file *seq, loff_t pos) +static void *ip_vs_conn_array(struct ip_vs_iter_state *iter) { int idx; struct ip_vs_conn *cp; - struct ip_vs_iter_state *iter = seq->private; - for (idx = 0; idx < ip_vs_conn_tab_size; idx++) { + for (idx = iter->bucket; idx < ip_vs_conn_tab_size; idx++) { + unsigned int skip = 0; + hlist_for_each_entry_rcu(cp, &ip_vs_conn_tab[idx], c_list) { /* __ip_vs_conn_get() is not needed by * ip_vs_conn_seq_show and ip_vs_conn_sync_seq_show */ - if (pos-- == 0) { - iter->l = &ip_vs_conn_tab[idx]; + if (skip >= iter->skip_elems) { + iter->bucket = idx; return cp; } + + ++skip; } + + iter->skip_elems = 0; cond_resched_rcu(); } + iter->bucket = idx; return NULL; } @@ -1076,9 +1083,14 @@ static void *ip_vs_conn_seq_start(struct seq_file *seq, loff_t *pos) { struct ip_vs_iter_state *iter = seq->private; - iter->l = NULL; rcu_read_lock(); - return *pos ? ip_vs_conn_array(seq, *pos - 1) :SEQ_START_TOKEN; + if (*pos == 0) { + iter->skip_elems = 0; + iter->bucket = 0; + return SEQ_START_TOKEN; + } + + return ip_vs_conn_array(iter); } static void *ip_vs_conn_seq_next(struct seq_file *seq, void *v, loff_t *pos) @@ -1086,28 +1098,22 @@ static void *ip_vs_conn_seq_next(struct seq_file *seq, void *v, loff_t *pos) struct ip_vs_conn *cp = v; struct ip_vs_iter_state *iter = seq->private; struct hlist_node *e; - struct hlist_head *l = iter->l; - int idx; ++*pos; if (v == SEQ_START_TOKEN) - return ip_vs_conn_array(seq, 0); + return ip_vs_conn_array(iter); /* more on same hash chain? */ e = rcu_dereference(hlist_next_rcu(&cp->c_list)); - if (e) + if (e) { + iter->skip_elems++; return hlist_entry(e, struct ip_vs_conn, c_list); - - idx = l - ip_vs_conn_tab; - while (++idx < ip_vs_conn_tab_size) { - hlist_for_each_entry_rcu(cp, &ip_vs_conn_tab[idx], c_list) { - iter->l = &ip_vs_conn_tab[idx]; - return cp; - } - cond_resched_rcu(); } - iter->l = NULL; - return NULL; + + iter->skip_elems = 0; + iter->bucket++; + + return ip_vs_conn_array(iter); } static void ip_vs_conn_seq_stop(struct seq_file *seq, void *v) -- 2.45.2