[RFC PATCH 27/30] net/netpolicy: fast path for finding the queues

kan.liang
2016-07-18T14:24:50Z

Current implementation searches the hash table to get assigned object
for each transmit/receive packet. It's not necessory, because the
assigned object usually remain unchanged.

This patch store the assigned queue into netpolicy_reg struct. So it
doesnot need to search the hash table everytime unless the system cpu
and queue mapping changed.

netpolicy_sys_map_version is used to track the system cpu and queue
mapping changes. It's protected by a rw lock (TODO: will replace by RCU
shortly).

Signed-off-by: Kan Liang <kan.liang@intel.com>
---
include/linux/init_task.h | 3 +++
include/linux/netpolicy.h | 5 +++++
kernel/fork.c | 3 +++
net/core/netpolicy.c | 36 ++++++++++++++++++++++++++++++++++++
net/core/sock.c | 6 ++++++
5 files changed, 53 insertions(+)

diff --git a/include/linux/init_task.h b/include/linux/init_task.h
index eda7ffc..06ea231 100644
--- a/include/linux/init_task.h
+++ b/include/linux/init_task.h
@@ -189,6 +189,9 @@ extern struct task_group root_task_group;
.task_netpolicy.dev = NULL, \
.task_netpolicy.location = ~0, \
.task_netpolicy.rule_queue = ~0, \
+ .task_netpolicy.rx_queue = ~0, \
+ .task_netpolicy.tx_queue = ~0, \
+ .task_netpolicy.sys_map_version = 0, \
.task_netpolicy.ptr = (void *)&tsk,
#else
#define INIT_NETPOLICY(tsk)
diff --git a/include/linux/netpolicy.h b/include/linux/netpolicy.h
index 1cd5ac4..fa740b5 100644
--- a/include/linux/netpolicy.h
+++ b/include/linux/netpolicy.h
@@ -39,6 +39,7 @@ enum netpolicy_traffic {

#define POLICY_NAME_LEN_MAX 64
extern const char *policy_name[];
+extern int netpolicy_sys_map_version __read_mostly;

struct netpolicy_dev_info {
u32 rx_num;
@@ -86,6 +87,10 @@ struct netpolicy_reg {
void *ptr; /* pointers */
u32 location; /* rule location */
u32 rule_queue; /* queue set by rule */
+ /* Info for fast path */
+ u32 rx_queue;
+ u32 tx_queue;
+ int sys_map_version;
};

struct netpolicy_tcpudpip4_spec {
diff --git a/kernel/fork.c b/kernel/fork.c
index 31262d2..fcb856b 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1456,6 +1456,9 @@ static struct task_struct *copy_process(unsigned long clone_flags,
#ifdef CONFIG_NETPOLICY
p->task_netpolicy.location = ~0;
p->task_netpolicy.rule_queue = ~0;
+ p->task_netpolicy.rx_queue = ~0;
+ p->task_netpolicy.tx_queue = ~0;
+ p->task_netpolicy.sys_map_version = 0;
p->task_netpolicy.ptr = (void *)p;
if (is_net_policy_valid(p->task_netpolicy.policy))
netpolicy_register(&p->task_netpolicy, p->task_netpolicy.policy);
diff --git a/net/core/netpolicy.c b/net/core/netpolicy.c
index 9e14137..a63ccd4 100644
--- a/net/core/netpolicy.c
+++ b/net/core/netpolicy.c
@@ -82,6 +82,10 @@ struct netpolicy_record {
static DEFINE_HASHTABLE(np_record_hash, 10);
static DEFINE_SPINLOCK(np_hashtable_lock);

+int netpolicy_sys_map_version;
+/* read write lock to protect sys map version */
+static DEFINE_RWLOCK(np_sys_map_lock);
+
static int netpolicy_get_dev_info(struct net_device *dev,
struct netpolicy_dev_info *d_info)
{
@@ -394,6 +398,24 @@ int netpolicy_pick_queue(struct netpolicy_reg *reg, bool is_rx)
(current->task_netpolicy.policy != reg->policy))
return -EINVAL;

+ /* fast path */
+ read_lock(&np_sys_map_lock);
+ if (netpolicy_sys_map_version == reg->sys_map_version) {
+ if (is_rx && (reg->rx_queue != ~0)) {
+ read_unlock(&np_sys_map_lock);
+ return reg->rx_queue;
+ }
+ if (!is_rx && (reg->tx_queue != ~0)) {
+ read_unlock(&np_sys_map_lock);
+ return reg->tx_queue;
+ }
+ } else {
+ reg->rx_queue = ~0;
+ reg->tx_queue = ~0;
+ reg->sys_map_version = netpolicy_sys_map_version;
+ }
+ read_unlock(&np_sys_map_lock);
+
old_record = netpolicy_record_search(ptr_id);
if (!old_record) {
pr_warn("NETPOLICY: doesn't registered. Remove net policy settings!\n");
@@ -435,6 +457,11 @@ int netpolicy_pick_queue(struct netpolicy_reg *reg, bool is_rx)
spin_unlock_bh(&np_hashtable_lock);
kfree(old_record);

+ if (is_rx)
+ reg->rx_queue = queue;
+ else
+ reg->tx_queue = queue;
+
return queue;

err:
@@ -522,6 +549,9 @@ void netpolicy_unregister(struct netpolicy_reg *reg)
rtnl_unlock();
reg->location = ~0;
reg->rule_queue = ~0;
+ reg->rx_queue = ~0;
+ reg->tx_queue = ~0;
+ reg->sys_map_version = 0;
}

spin_lock_bh(&np_hashtable_lock);
@@ -1272,6 +1302,10 @@ void update_netpolicy_sys_map(void)
netpolicy_disable(dev);
goto unlock;
}
+ write_lock(&np_sys_map_lock);
+ if (netpolicy_sys_map_version++ < 0)
+ netpolicy_sys_map_version = 0;
+ write_unlock(&np_sys_map_lock);

dev->netpolicy->cur_policy = cur_policy;
unlock:
@@ -1305,6 +1339,8 @@ static int __init netpolicy_init(void)
{
int ret;

+ netpolicy_sys_map_version = 0;
+
ret = register_pernet_subsys(&netpolicy_net_ops);
if (!ret)
register_netdevice_notifier(&netpolicy_dev_notf);
diff --git a/net/core/sock.c b/net/core/sock.c
index 4d47a89..284aafd 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1447,6 +1447,9 @@ struct sock *sk_alloc(struct net *net, int family, gfp_t priority,
sk->sk_netpolicy.policy = NET_POLICY_INVALID;
sk->sk_netpolicy.location = ~0;
sk->sk_netpolicy.rule_queue = ~0;
+ sk->sk_netpolicy.rx_queue = ~0;
+ sk->sk_netpolicy.tx_queue = ~0;
+ sk->sk_netpolicy.sys_map_version = 0;
#endif
}

@@ -1630,6 +1633,9 @@ struct sock *sk_clone_lock(const struct sock *sk, const gfp_t priority)
newsk->sk_netpolicy.ptr = (void *)newsk;
newsk->sk_netpolicy.location = ~0;
newsk->sk_netpolicy.rule_queue = ~0;
+ newsk->sk_netpolicy.rx_queue = ~0;
+ newsk->sk_netpolicy.tx_queue = ~0;
+ newsk->sk_netpolicy.sys_map_version = 0;
if (is_net_policy_valid(current->task_netpolicy.policy))
newsk->sk_netpolicy.policy = NET_POLICY_INVALID;
if (is_net_policy_valid(newsk->sk_netpolicy.policy))
--
2.5.5