xfrm: select sane defaults for xfrm[4|6] gc_thresh
Choose saner defaults for xfrm[4|6] gc_thresh values on init
Currently, the xfrm[4|6] code has hard-coded initial gc_thresh values
(set to 1024). Given that the ipv4 and ipv6 routing caches are sized
dynamically at boot time, the static selections can be non-sensical.
This patch dynamically selects an appropriate gc threshold based on
the corresponding main routing table size, using the assumption that
we should in the worst case be able to handle as many connections as
the routing table can.
For ipv4, the maximum route cache size is 16 * the number of hash
buckets in the route cache. Given that xfrm4 starts garbage
collection at the gc_thresh and prevents new allocations at 2 *
gc_thresh, we set gc_thresh to half the maximum route cache size.
For ipv6, its a bit trickier. there is no maximum route cache size,
but the ipv6 dst_ops gc_thresh is statically set to 1024. It seems
sane to select a simmilar gc_thresh for the xfrm6 code that is half
the number of hash buckets in the v6 route cache times 16 (like the v4
code does).
Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/ip6_fib.h b/include/net/ip6_fib.h
index 7c5c0f7..15b492a 100644
--- a/include/net/ip6_fib.h
+++ b/include/net/ip6_fib.h
@@ -22,6 +22,12 @@
#include <net/flow.h>
#include <net/netlink.h>
+#ifdef CONFIG_IPV6_MULTIPLE_TABLES
+#define FIB6_TABLE_HASHSZ 256
+#else
+#define FIB6_TABLE_HASHSZ 1
+#endif
+
struct rt6_info;
struct fib6_config
diff --git a/include/net/xfrm.h b/include/net/xfrm.h
index 9e3a3f4..223e90a 100644
--- a/include/net/xfrm.h
+++ b/include/net/xfrm.h
@@ -1280,7 +1280,7 @@
};
extern void xfrm_init(void);
-extern void xfrm4_init(void);
+extern void xfrm4_init(int rt_hash_size);
extern int xfrm_state_init(struct net *net);
extern void xfrm_state_fini(struct net *net);
extern void xfrm4_state_init(void);
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index 278f46f..fafbe16 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -3442,7 +3442,7 @@
printk(KERN_ERR "Unable to create route proc files\n");
#ifdef CONFIG_XFRM
xfrm_init();
- xfrm4_init();
+ xfrm4_init(ip_rt_max_size);
#endif
rtnl_register(PF_INET, RTM_GETROUTE, inet_rtm_getroute, NULL);
diff --git a/net/ipv4/xfrm4_policy.c b/net/ipv4/xfrm4_policy.c
index 26496ba..1ba4474 100644
--- a/net/ipv4/xfrm4_policy.c
+++ b/net/ipv4/xfrm4_policy.c
@@ -290,10 +290,21 @@
xfrm_policy_unregister_afinfo(&xfrm4_policy_afinfo);
}
-void __init xfrm4_init(void)
+void __init xfrm4_init(int rt_max_size)
{
xfrm4_state_init();
xfrm4_policy_init();
+ /*
+ * Select a default value for the gc_thresh based on the main route
+ * table hash size. It seems to me the worst case scenario is when
+ * we have ipsec operating in transport mode, in which we create a
+ * dst_entry per socket. The xfrm gc algorithm starts trying to remove
+ * entries at gc_thresh, and prevents new allocations as 2*gc_thresh
+ * so lets set an initial xfrm gc_thresh value at the rt_max_size/2.
+ * That will let us store an ipsec connection per route table entry,
+ * and start cleaning when were 1/2 full
+ */
+ xfrm4_dst_ops.gc_thresh = rt_max_size/2;
sysctl_hdr = register_net_sysctl_table(&init_net, net_ipv4_ctl_path,
xfrm4_policy_table);
}
diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
index 52ee1dc..0e93ca5 100644
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -164,12 +164,6 @@
dst_free(&rt->u.dst);
}
-#ifdef CONFIG_IPV6_MULTIPLE_TABLES
-#define FIB_TABLE_HASHSZ 256
-#else
-#define FIB_TABLE_HASHSZ 1
-#endif
-
static void fib6_link_table(struct net *net, struct fib6_table *tb)
{
unsigned int h;
@@ -180,7 +174,7 @@
*/
rwlock_init(&tb->tb6_lock);
- h = tb->tb6_id & (FIB_TABLE_HASHSZ - 1);
+ h = tb->tb6_id & (FIB6_TABLE_HASHSZ - 1);
/*
* No protection necessary, this is the only list mutatation
@@ -231,7 +225,7 @@
if (id == 0)
id = RT6_TABLE_MAIN;
- h = id & (FIB_TABLE_HASHSZ - 1);
+ h = id & (FIB6_TABLE_HASHSZ - 1);
rcu_read_lock();
head = &net->ipv6.fib_table_hash[h];
hlist_for_each_entry_rcu(tb, node, head, tb6_hlist) {
@@ -382,7 +376,7 @@
arg.net = net;
w->args = &arg;
- for (h = s_h; h < FIB_TABLE_HASHSZ; h++, s_e = 0) {
+ for (h = s_h; h < FIB6_TABLE_HASHSZ; h++, s_e = 0) {
e = 0;
head = &net->ipv6.fib_table_hash[h];
hlist_for_each_entry(tb, node, head, tb6_hlist) {
@@ -1368,7 +1362,7 @@
unsigned int h;
rcu_read_lock();
- for (h = 0; h < FIB_TABLE_HASHSZ; h++) {
+ for (h = 0; h < FIB6_TABLE_HASHSZ; h++) {
head = &net->ipv6.fib_table_hash[h];
hlist_for_each_entry_rcu(table, node, head, tb6_hlist) {
write_lock_bh(&table->tb6_lock);
@@ -1483,7 +1477,7 @@
if (!net->ipv6.rt6_stats)
goto out_timer;
- net->ipv6.fib_table_hash = kcalloc(FIB_TABLE_HASHSZ,
+ net->ipv6.fib_table_hash = kcalloc(FIB6_TABLE_HASHSZ,
sizeof(*net->ipv6.fib_table_hash),
GFP_KERNEL);
if (!net->ipv6.fib_table_hash)
diff --git a/net/ipv6/xfrm6_policy.c b/net/ipv6/xfrm6_policy.c
index 4acc308..611cffc 100644
--- a/net/ipv6/xfrm6_policy.c
+++ b/net/ipv6/xfrm6_policy.c
@@ -323,6 +323,7 @@
int __init xfrm6_init(void)
{
int ret;
+ unsigned int gc_thresh;
ret = xfrm6_policy_init();
if (ret)
@@ -331,6 +332,20 @@
ret = xfrm6_state_init();
if (ret)
goto out_policy;
+ /*
+ * We need a good default value for the xfrm6 gc threshold.
+ * In ipv4 we set it to the route hash table size * 8, which
+ * is half the size of the maximaum route cache for ipv4. It
+ * would be good to do the same thing for v6, except the table is
+ * constructed differently here. Here each table for a net namespace
+ * can have FIB_TABLE_HASHSZ entries, so lets go with the same
+ * computation that we used for ipv4 here. Also, lets keep the initial
+ * gc_thresh to a minimum of 1024, since, the ipv6 route cache defaults
+ * to that as a minimum as well
+ */
+ gc_thresh = FIB6_TABLE_HASHSZ * 8;
+ xfrm6_dst_ops.gc_thresh = (gc_thresh < 1024) ? 1024 : gc_thresh;
+
sysctl_hdr = register_net_sysctl_table(&init_net, net_ipv6_ctl_path,
xfrm6_policy_table);
out: