tcp/dccp: get rid of central timewait timer
Using a timer wheel for timewait sockets was nice ~15 years ago when
memory was expensive and machines had a single processor.
This does not scale, code is ugly and source of huge latencies
(Typically 30 ms have been seen, cpus spinning on death_lock spinlock.)
We can afford to use an extra 64 bytes per timewait sock and spread
timewait load to all cpus to have better behavior.
Tested:
On following test, /proc/sys/net/ipv4/tcp_tw_recycle is set to 1
on the target (lpaa24)
Before patch :
lpaa23:~# ./super_netperf 200 -H lpaa24 -t TCP_CC -l 60 -- -p0,0
419594
lpaa23:~# ./super_netperf 200 -H lpaa24 -t TCP_CC -l 60 -- -p0,0
437171
While test is running, we can observe 25 or even 33 ms latencies.
lpaa24:~# ping -c 1000 -i 0.02 -qn lpaa23
...
1000 packets transmitted, 1000 received, 0% packet loss, time 20601ms
rtt min/avg/max/mdev = 0.020/0.217/25.771/1.535 ms, pipe 2
lpaa24:~# ping -c 1000 -i 0.02 -qn lpaa23
...
1000 packets transmitted, 1000 received, 0% packet loss, time 20702ms
rtt min/avg/max/mdev = 0.019/0.183/33.761/1.441 ms, pipe 2
After patch :
About 90% increase of throughput :
lpaa23:~# ./super_netperf 200 -H lpaa24 -t TCP_CC -l 60 -- -p0,0
810442
lpaa23:~# ./super_netperf 200 -H lpaa24 -t TCP_CC -l 60 -- -p0,0
800992
And latencies are kept to minimal values during this load, even
if network utilization is 90% higher :
lpaa24:~# ping -c 1000 -i 0.02 -qn lpaa23
...
1000 packets transmitted, 1000 received, 0% packet loss, time 19991ms
rtt min/avg/max/mdev = 0.023/0.064/0.360/0.042 ms
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/inet_timewait_sock.h b/include/net/inet_timewait_sock.h
index b7ce100..360c480 100644
--- a/include/net/inet_timewait_sock.h
+++ b/include/net/inet_timewait_sock.h
@@ -31,67 +31,14 @@
struct inet_hashinfo;
-#define INET_TWDR_RECYCLE_SLOTS_LOG 5
-#define INET_TWDR_RECYCLE_SLOTS (1 << INET_TWDR_RECYCLE_SLOTS_LOG)
-
-/*
- * If time > 4sec, it is "slow" path, no recycling is required,
- * so that we select tick to get range about 4 seconds.
- */
-#if HZ <= 16 || HZ > 4096
-# error Unsupported: HZ <= 16 or HZ > 4096
-#elif HZ <= 32
-# define INET_TWDR_RECYCLE_TICK (5 + 2 - INET_TWDR_RECYCLE_SLOTS_LOG)
-#elif HZ <= 64
-# define INET_TWDR_RECYCLE_TICK (6 + 2 - INET_TWDR_RECYCLE_SLOTS_LOG)
-#elif HZ <= 128
-# define INET_TWDR_RECYCLE_TICK (7 + 2 - INET_TWDR_RECYCLE_SLOTS_LOG)
-#elif HZ <= 256
-# define INET_TWDR_RECYCLE_TICK (8 + 2 - INET_TWDR_RECYCLE_SLOTS_LOG)
-#elif HZ <= 512
-# define INET_TWDR_RECYCLE_TICK (9 + 2 - INET_TWDR_RECYCLE_SLOTS_LOG)
-#elif HZ <= 1024
-# define INET_TWDR_RECYCLE_TICK (10 + 2 - INET_TWDR_RECYCLE_SLOTS_LOG)
-#elif HZ <= 2048
-# define INET_TWDR_RECYCLE_TICK (11 + 2 - INET_TWDR_RECYCLE_SLOTS_LOG)
-#else
-# define INET_TWDR_RECYCLE_TICK (12 + 2 - INET_TWDR_RECYCLE_SLOTS_LOG)
-#endif
-
-static inline u32 inet_tw_time_stamp(void)
-{
- return jiffies;
-}
-
-/* TIME_WAIT reaping mechanism. */
-#define INET_TWDR_TWKILL_SLOTS 8 /* Please keep this a power of 2. */
-
-#define INET_TWDR_TWKILL_QUOTA 100
-
struct inet_timewait_death_row {
- /* Short-time timewait calendar */
- int twcal_hand;
- unsigned long twcal_jiffie;
- struct timer_list twcal_timer;
- struct hlist_head twcal_row[INET_TWDR_RECYCLE_SLOTS];
+ atomic_t tw_count;
- spinlock_t death_lock;
- int tw_count;
- int period;
- u32 thread_slots;
- struct work_struct twkill_work;
- struct timer_list tw_timer;
- int slot;
- struct hlist_head cells[INET_TWDR_TWKILL_SLOTS];
- struct inet_hashinfo *hashinfo;
+ struct inet_hashinfo *hashinfo ____cacheline_aligned_in_smp;
int sysctl_tw_recycle;
int sysctl_max_tw_buckets;
};
-void inet_twdr_hangman(unsigned long data);
-void inet_twdr_twkill_work(struct work_struct *work);
-void inet_twdr_twcal_tick(unsigned long data);
-
struct inet_bind_bucket;
/*
@@ -133,52 +80,18 @@
__be16 tw_sport;
kmemcheck_bitfield_begin(flags);
/* And these are ours. */
- unsigned int tw_pad0 : 1, /* 1 bit hole */
+ unsigned int tw_kill : 1,
tw_transparent : 1,
tw_flowlabel : 20,
tw_pad : 2, /* 2 bits hole */
tw_tos : 8;
kmemcheck_bitfield_end(flags);
- u32 tw_ttd;
+ struct timer_list tw_timer;
struct inet_bind_bucket *tw_tb;
- struct hlist_node tw_death_node;
+ struct inet_timewait_death_row *tw_dr;
};
#define tw_tclass tw_tos
-static inline int inet_twsk_dead_hashed(const struct inet_timewait_sock *tw)
-{
- return !hlist_unhashed(&tw->tw_death_node);
-}
-
-static inline void inet_twsk_dead_node_init(struct inet_timewait_sock *tw)
-{
- tw->tw_death_node.pprev = NULL;
-}
-
-static inline void __inet_twsk_del_dead_node(struct inet_timewait_sock *tw)
-{
- __hlist_del(&tw->tw_death_node);
- inet_twsk_dead_node_init(tw);
-}
-
-static inline int inet_twsk_del_dead_node(struct inet_timewait_sock *tw)
-{
- if (inet_twsk_dead_hashed(tw)) {
- __inet_twsk_del_dead_node(tw);
- return 1;
- }
- return 0;
-}
-
-#define inet_twsk_for_each(tw, node, head) \
- hlist_nulls_for_each_entry(tw, node, head, tw_node)
-
-#define inet_twsk_for_each_inmate(tw, jail) \
- hlist_for_each_entry(tw, jail, tw_death_node)
-
-#define inet_twsk_for_each_inmate_safe(tw, safe, jail) \
- hlist_for_each_entry_safe(tw, safe, jail, tw_death_node)
-
static inline struct inet_timewait_sock *inet_twsk(const struct sock *sk)
{
return (struct inet_timewait_sock *)sk;
@@ -193,16 +106,14 @@
struct inet_hashinfo *hashinfo);
struct inet_timewait_sock *inet_twsk_alloc(const struct sock *sk,
+ struct inet_timewait_death_row *dr,
const int state);
void __inet_twsk_hashdance(struct inet_timewait_sock *tw, struct sock *sk,
struct inet_hashinfo *hashinfo);
-void inet_twsk_schedule(struct inet_timewait_sock *tw,
- struct inet_timewait_death_row *twdr,
- const int timeo, const int timewait_len);
-void inet_twsk_deschedule(struct inet_timewait_sock *tw,
- struct inet_timewait_death_row *twdr);
+void inet_twsk_schedule(struct inet_timewait_sock *tw, const int timeo);
+void inet_twsk_deschedule(struct inet_timewait_sock *tw);
void inet_twsk_purge(struct inet_hashinfo *hashinfo,
struct inet_timewait_death_row *twdr, int family);