tuntap: reduce memory using of queues

[~andy/linux] / drivers / net / tun.c

diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index c81680dc10eb7c43baaf61a0bfea1456dbe33c5c..8939d2117de2420784ba524cfc013bb85aaa5f92 100644 (file)
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -109,11 +109,10 @@ struct tap_filter {
        unsigned char   addr[FLT_EXACT_COUNT][ETH_ALEN];
 };
 
-/* 1024 is probably a high enough limit: modern hypervisors seem to support on
- * the order of 100-200 CPUs so this leaves us some breathing space if we want
- * to match a queue per guest CPU.
- */
-#define MAX_TAP_QUEUES 1024
+/* DEFAULT_MAX_NUM_RSS_QUEUES were choosed to let the rx/tx queues allocated for
+ * the netdevice to be fit in one page. So we can make sure the success of
+ * memory allocation. TODO: increase the limit. */
+#define MAX_TAP_QUEUES DEFAULT_MAX_NUM_RSS_QUEUES
 
 #define TUN_FLOW_EXPIRE (3 * HZ)
 
@@ -1583,6 +1582,8 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
        else {
                char *name;
                unsigned long flags = 0;
+               int queues = ifr->ifr_flags & IFF_MULTI_QUEUE ?
+                            MAX_TAP_QUEUES : 1;
 
                if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
                        return -EPERM;
@@ -1606,8 +1607,8 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr)
                        name = ifr->ifr_name;
 
                dev = alloc_netdev_mqs(sizeof(struct tun_struct), name,
-                                      tun_setup,
-                                      MAX_TAP_QUEUES, MAX_TAP_QUEUES);
+                                      tun_setup, queues, queues);
+
                if (!dev)
                        return -ENOMEM;