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Commit 5d48ef3e authored by David S. Miller's avatar David S. Miller
Browse files

Merge branch 'tcp_mem_pressure' 



Eric Dumazet says:

====================
tcp: better handling of memory pressure

When testing commit 790ba456 ("tcp: set SOCK_NOSPACE under memory
pressure") using edge triggered epoll applications, I found various
issues under memory pressure and thousands of active sockets.

This patch series is a first round to solve these issues, in send
and receive paths. There are probably other fixes needed, but
with this series, my tests now all succeed.

v2: fix typo in "allow one skb to be received per socket under memory pressure",
as spotted by Jason Baron.
====================

Acked-by: default avatarJason Baron <jbaron@akamai.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parents 4633c9e0 b66e91cc

include/net/sock.h

+3 −3
Original line number Diff line number Diff line
@@ -1368,7 +1368,7 @@ static inline struct inode *SOCK_INODE(struct socket *socket) 
 * Functions for memory accounting

 */

int __sk_mem_schedule(struct sock *sk, int size, int kind);

void __sk_mem_reclaim(struct sock *sk);

void __sk_mem_reclaim(struct sock *sk, int amount);



#define SK_MEM_QUANTUM ((int)PAGE_SIZE)

#define SK_MEM_QUANTUM_SHIFT ilog2(SK_MEM_QUANTUM)
@@ -1409,7 +1409,7 @@ static inline void sk_mem_reclaim(struct sock *sk) 
	if (!sk_has_account(sk))

		return;

	if (sk->sk_forward_alloc >= SK_MEM_QUANTUM)

		__sk_mem_reclaim(sk);

		__sk_mem_reclaim(sk, sk->sk_forward_alloc);

}



static inline void sk_mem_reclaim_partial(struct sock *sk)
@@ -1417,7 +1417,7 @@ static inline void sk_mem_reclaim_partial(struct sock *sk) 
	if (!sk_has_account(sk))

		return;

	if (sk->sk_forward_alloc > SK_MEM_QUANTUM)

		__sk_mem_reclaim(sk);

		__sk_mem_reclaim(sk, sk->sk_forward_alloc - 1);

}



static inline void sk_mem_charge(struct sock *sk, int size)

include/net/tcp.h

+10 −0
Original line number Diff line number Diff line
@@ -286,6 +286,14 @@ extern atomic_long_t tcp_memory_allocated; 
extern struct percpu_counter tcp_sockets_allocated;

extern int tcp_memory_pressure;



/* optimized version of sk_under_memory_pressure() for TCP sockets */

static inline bool tcp_under_memory_pressure(const struct sock *sk)

{

	if (mem_cgroup_sockets_enabled && sk->sk_cgrp)

		return !!sk->sk_cgrp->memory_pressure;



	return tcp_memory_pressure;

}

/*

 * The next routines deal with comparing 32 bit unsigned ints

 * and worry about wraparound (automatic with unsigned arithmetic).
@@ -311,6 +319,8 @@ static inline bool tcp_out_of_memory(struct sock *sk) 
	return false;

}



void sk_forced_mem_schedule(struct sock *sk, int size);



static inline bool tcp_too_many_orphans(struct sock *sk, int shift)

{

	struct percpu_counter *ocp = sk->sk_prot->orphan_count;

net/core/sock.c

+5 −4
Original line number Diff line number Diff line
@@ -2069,12 +2069,13 @@ EXPORT_SYMBOL(__sk_mem_schedule); 
/**

 *	__sk_reclaim - reclaim memory_allocated

 *	@sk: socket

 *	@amount: number of bytes (rounded down to a SK_MEM_QUANTUM multiple)

 */

void __sk_mem_reclaim(struct sock *sk)

void __sk_mem_reclaim(struct sock *sk, int amount)

{

	sk_memory_allocated_sub(sk,

				sk->sk_forward_alloc >> SK_MEM_QUANTUM_SHIFT);

	sk->sk_forward_alloc &= SK_MEM_QUANTUM - 1;

	amount >>= SK_MEM_QUANTUM_SHIFT;

	sk_memory_allocated_sub(sk, amount);

	sk->sk_forward_alloc -= amount << SK_MEM_QUANTUM_SHIFT;



	if (sk_under_memory_pressure(sk) &&

	    (sk_memory_allocated(sk) < sk_prot_mem_limits(sk, 0)))

net/ipv4/tcp.c

+18 −6
Original line number Diff line number Diff line
@@ -815,9 +815,20 @@ struct sk_buff *sk_stream_alloc_skb(struct sock *sk, int size, gfp_t gfp) 
	/* The TCP header must be at least 32-bit aligned.  */

	size = ALIGN(size, 4);



	if (unlikely(tcp_under_memory_pressure(sk)))

		sk_mem_reclaim_partial(sk);



	skb = alloc_skb_fclone(size + sk->sk_prot->max_header, gfp);

	if (skb) {

		if (sk_wmem_schedule(sk, skb->truesize)) {

	if (likely(skb)) {

		bool mem_schedule;



		if (skb_queue_len(&sk->sk_write_queue) == 0) {

			mem_schedule = true;

			sk_forced_mem_schedule(sk, skb->truesize);

		} else {

			mem_schedule = sk_wmem_schedule(sk, skb->truesize);

		}

		if (likely(mem_schedule)) {

			skb_reserve(skb, sk->sk_prot->max_header);

			/*

			 * Make sure that we have exactly size bytes
@@ -3057,11 +3068,12 @@ __setup("thash_entries=", set_thash_entries); 


static void __init tcp_init_mem(void)

{

	unsigned long limit = nr_free_buffer_pages() / 8;

	unsigned long limit = nr_free_buffer_pages() / 16;



	limit = max(limit, 128UL);

	sysctl_tcp_mem[0] = limit / 4 * 3;

	sysctl_tcp_mem[1] = limit;

	sysctl_tcp_mem[2] = sysctl_tcp_mem[0] * 2;

	sysctl_tcp_mem[0] = limit / 4 * 3;		/* 4.68 % */

	sysctl_tcp_mem[1] = limit;			/* 6.25 % */

	sysctl_tcp_mem[2] = sysctl_tcp_mem[0] * 2;	/* 9.37 % */

}



void __init tcp_init(void)

net/ipv4/tcp_input.c

+10 −8
Original line number Diff line number Diff line
@@ -359,7 +359,7 @@ static void tcp_grow_window(struct sock *sk, const struct sk_buff *skb) 
	/* Check #1 */

	if (tp->rcv_ssthresh < tp->window_clamp &&

	    (int)tp->rcv_ssthresh < tcp_space(sk) &&

	    !sk_under_memory_pressure(sk)) {

	    !tcp_under_memory_pressure(sk)) {

		int incr;



		/* Check #2. Increase window, if skb with such overhead
@@ -446,7 +446,7 @@ static void tcp_clamp_window(struct sock *sk) 


	if (sk->sk_rcvbuf < sysctl_tcp_rmem[2] &&

	    !(sk->sk_userlocks & SOCK_RCVBUF_LOCK) &&

	    !sk_under_memory_pressure(sk) &&

	    !tcp_under_memory_pressure(sk) &&

	    sk_memory_allocated(sk) < sk_prot_mem_limits(sk, 0)) {

		sk->sk_rcvbuf = min(atomic_read(&sk->sk_rmem_alloc),

				    sysctl_tcp_rmem[2]);
@@ -4507,10 +4507,12 @@ static void tcp_data_queue(struct sock *sk, struct sk_buff *skb) 


		if (eaten <= 0) {

queue_and_out:

			if (eaten < 0 &&

			    tcp_try_rmem_schedule(sk, skb, skb->truesize))

			if (eaten < 0) {

				if (skb_queue_len(&sk->sk_receive_queue) == 0)

					sk_forced_mem_schedule(sk, skb->truesize);

				else if (tcp_try_rmem_schedule(sk, skb, skb->truesize))

					goto drop;



			}

			eaten = tcp_queue_rcv(sk, skb, 0, &fragstolen);

		}

		tcp_rcv_nxt_update(tp, TCP_SKB_CB(skb)->end_seq);
@@ -4781,7 +4783,7 @@ static int tcp_prune_queue(struct sock *sk) 


	if (atomic_read(&sk->sk_rmem_alloc) >= sk->sk_rcvbuf)

		tcp_clamp_window(sk);

	else if (sk_under_memory_pressure(sk))

	else if (tcp_under_memory_pressure(sk))

		tp->rcv_ssthresh = min(tp->rcv_ssthresh, 4U * tp->advmss);



	tcp_collapse_ofo_queue(sk);
@@ -4825,7 +4827,7 @@ static bool tcp_should_expand_sndbuf(const struct sock *sk) 
		return false;



	/* If we are under global TCP memory pressure, do not expand.  */

	if (sk_under_memory_pressure(sk))

	if (tcp_under_memory_pressure(sk))

		return false;



	/* If we are under soft global TCP memory pressure, do not expand.  */