Messages in this thread Patch in this message | | | From | Pankaj Gupta <> | Subject | [RFC 3/4] tuntap: reduce the size of tun_struct by using flex array | Date | Mon, 18 Aug 2014 19:07:19 +0530 |
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This patch switches to flex array to implement the flow caches, it brings several advantages:
- Reduce the size of the tun_struct structure, which allows us to increase the upper limit of queues in future. - Avoid higher order memory allocation. It will be useful when switching to pure hashing in flow cache which may demand a larger size array in future.
After this patch, the size of tun_struct on x86_64 reduced from 8512 to 328
Signed-off-by: Jason Wang <jasowang@redhat.com> Signed-off-by: Pankaj Gupta <pagupta@redhat.com> --- drivers/net/tun.c | 49 +++++++++++++++++++++++++++++++++++++------------ 1 files changed, 37 insertions(+), 12 deletions(-)
diff --git a/drivers/net/tun.c b/drivers/net/tun.c index acaaf67..7dd495f 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -65,6 +65,7 @@ #include <linux/nsproxy.h> #include <linux/virtio_net.h> #include <linux/rcupdate.h> +#include <linux/flex_array.h> #include <net/net_namespace.h> #include <net/netns/generic.h> #include <net/rtnetlink.h> @@ -186,7 +187,7 @@ struct tun_struct { int debug; #endif spinlock_t lock; - struct hlist_head flows[TUN_NUM_FLOW_ENTRIES]; + struct flex_array *flows; struct timer_list flow_gc_timer; unsigned long ageing_time; unsigned int numdisabled; @@ -247,10 +248,11 @@ static void tun_flow_flush(struct tun_struct *tun) spin_lock_bh(&tun->lock); for (i = 0; i < TUN_NUM_FLOW_ENTRIES; i++) { + struct hlist_head *h = flex_array_get(tun->flows, i); struct tun_flow_entry *e; struct hlist_node *n; - hlist_for_each_entry_safe(e, n, &tun->flows[i], hash_link) + hlist_for_each_entry_safe(e, n, h, hash_link) tun_flow_delete(tun, e); } spin_unlock_bh(&tun->lock); @@ -262,10 +264,11 @@ static void tun_flow_delete_by_queue(struct tun_struct *tun, u16 queue_index) spin_lock_bh(&tun->lock); for (i = 0; i < TUN_NUM_FLOW_ENTRIES; i++) { + struct hlist_head *h = flex_array_get(tun->flows, i); struct tun_flow_entry *e; struct hlist_node *n; - hlist_for_each_entry_safe(e, n, &tun->flows[i], hash_link) { + hlist_for_each_entry_safe(e, n, h, hash_link) { if (e->queue_index == queue_index) tun_flow_delete(tun, e); } @@ -285,10 +288,11 @@ static void tun_flow_cleanup(unsigned long data) spin_lock_bh(&tun->lock); for (i = 0; i < TUN_NUM_FLOW_ENTRIES; i++) { + struct hlist_head *h = flex_array_get(tun->flows, i); struct tun_flow_entry *e; struct hlist_node *n; - hlist_for_each_entry_safe(e, n, &tun->flows[i], hash_link) { + hlist_for_each_entry_safe(e, n, h, hash_link) { unsigned long this_timer; count++; this_timer = e->updated + delay; @@ -315,7 +319,7 @@ static void tun_flow_update(struct tun_struct *tun, u32 rxhash, if (!rxhash) return; else - head = &tun->flows[tun_hashfn(rxhash)]; + head = flex_array_get(tun->flows, tun_hashfn(rxhash)); rcu_read_lock(); @@ -378,7 +382,8 @@ static u16 tun_select_queue(struct net_device *dev, struct sk_buff *skb, txq = skb_get_hash(skb); if (txq) { - e = tun_flow_find(&tun->flows[tun_hashfn(txq)], txq); + e = tun_flow_find(flex_array_get(tun->flows, + tun_hashfn(txq)), txq); if (e) { tun_flow_save_rps_rxhash(e, txq); txq = e->queue_index; @@ -758,8 +763,8 @@ static netdev_tx_t tun_net_xmit(struct sk_buff *skb, struct net_device *dev) rxhash = skb_get_hash(skb); if (rxhash) { struct tun_flow_entry *e; - e = tun_flow_find(&tun->flows[tun_hashfn(rxhash)], - rxhash); + e = tun_flow_find(flex_array_get(tun->flows, + tun_hashfn(rxhash)), rxhash); if (e) tun_flow_save_rps_rxhash(e, rxhash); } @@ -894,23 +899,40 @@ static const struct net_device_ops tap_netdev_ops = { #endif }; -static void tun_flow_init(struct tun_struct *tun) +static int tun_flow_init(struct tun_struct *tun) { - int i; + struct flex_array *buckets; + int i, err; + + buckets = flex_array_alloc(sizeof(struct hlist_head), + TUN_NUM_FLOW_ENTRIES, GFP_KERNEL); + if (!buckets) + return -ENOMEM; + + err = flex_array_prealloc(buckets, 0, TUN_NUM_FLOW_ENTRIES, GFP_KERNEL); + if (err) { + flex_array_free(buckets); + return -ENOMEM; + } + tun->flows = buckets; for (i = 0; i < TUN_NUM_FLOW_ENTRIES; i++) - INIT_HLIST_HEAD(&tun->flows[i]); + INIT_HLIST_HEAD((struct hlist_head *) + flex_array_get(buckets, i)); tun->ageing_time = TUN_FLOW_EXPIRE; setup_timer(&tun->flow_gc_timer, tun_flow_cleanup, (unsigned long)tun); mod_timer(&tun->flow_gc_timer, round_jiffies_up(jiffies + tun->ageing_time)); + + return 0; } static void tun_flow_uninit(struct tun_struct *tun) { del_timer_sync(&tun->flow_gc_timer); tun_flow_flush(tun); + flex_array_free(tun->flows); } /* Initialize net device. */ @@ -1659,7 +1681,10 @@ static int tun_set_iff(struct net *net, struct file *file, struct ifreq *ifr) goto err_free_dev; tun_net_init(dev); - tun_flow_init(tun); + + err = tun_flow_init(tun); + if (err < 0) + goto err_free_dev; dev->hw_features = NETIF_F_SG | NETIF_F_FRAGLIST | TUN_USER_FEATURES | NETIF_F_HW_VLAN_CTAG_TX | -- 1.7.1
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