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Message-Id: <1371620452-49349-3-git-send-email-jasowang@redhat.com>
Date: Wed, 19 Jun 2013 13:40:51 +0800
From: Jason Wang <jasowang@...hat.com>
To: davem@...emloft.net, edumazet@...gle.com, hkchu@...gle.com,
mst@...hat.com, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org
Cc: Jason Wang <jasowang@...hat.com>
Subject: [net-next rfc 2/3] tuntap: reduce the size of tun_struct by using flex array
This patch switches to use flex array to implement the flow caches, it can
brings several advantages:
- save the size of the tun_struct structure, which can allows us to increase the
upper limit of queues in the future.
- avoid higher order memory allocation which could be used when switching to use
pure hashing in flow cache who may demand a larger size array in the future.
After this patch, the size of tun_struct on x86_64 were reduced from 8512 to
328.
Signed-off-by: Jason Wang <jasowang@...hat.com>
---
drivers/net/tun.c | 54 +++++++++++++++++++++++++++++++++++++----------
net/openvswitch/flow.c | 2 +-
2 files changed, 43 insertions(+), 13 deletions(-)
diff --git a/drivers/net/tun.c b/drivers/net/tun.c
index a344270..8c5c124 100644
--- a/drivers/net/tun.c
+++ b/drivers/net/tun.c
@@ -64,6 +64,7 @@
#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>
@@ -180,7 +181,7 @@ 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;
@@ -239,10 +240,11 @@ 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);
@@ -254,10 +256,11 @@ 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);
}
@@ -277,10 +280,11 @@ 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;
@@ -307,7 +311,7 @@ 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();
@@ -356,7 +360,8 @@ static u16 tun_select_queue(struct net_device *dev, struct sk_buff *skb)
txq = skb_get_rxhash(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)
txq = e->queue_index;
else
@@ -841,23 +846,45 @@ 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, bool mq)
{
- int i;
+ struct flex_array *buckets;
+ int i, err;
+
+ if (!mq)
+ return 0;
+
+ 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);
+ if (tun->flags & TUN_TAP_MQ) {
+ del_timer_sync(&tun->flow_gc_timer);
+ tun_flow_flush(tun);
+ flex_array_free(tun->flows);
+ }
}
/* Initialize net device. */
@@ -1660,7 +1687,10 @@ 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, queues > 1);
+ if (err < 0)
+ goto err_free_dev;
dev->hw_features = NETIF_F_SG | NETIF_F_FRAGLIST |
TUN_USER_FEATURES;
diff --git a/net/openvswitch/flow.c b/net/openvswitch/flow.c
index 093c191..5787acc 100644
--- a/net/openvswitch/flow.c
+++ b/net/openvswitch/flow.c
@@ -241,7 +241,7 @@ static struct flex_array *alloc_buckets(unsigned int n_buckets)
struct flex_array *buckets;
int i, err;
- buckets = flex_array_alloc(sizeof(struct hlist_head *),
+ buckets = flex_array_alloc(sizeof(struct hlist_head),
n_buckets, GFP_KERNEL);
if (!buckets)
return NULL;
--
1.7.1
--
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