Commit 3cd3399d authored by Eric Dumazet's avatar Eric Dumazet Committed by Jakub Kicinski
Browse files

net: implement per-cpu reserves for memory_allocated 



We plan keeping sk->sk_forward_alloc as small as possible
in future patches.

This means we are going to call sk_memory_allocated_add()
and sk_memory_allocated_sub() more often.

Implement a per-cpu cache of +1/-1 MB, to reduce number
of changes to sk->sk_prot->memory_allocated, which
would otherwise be cause of false sharing.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Acked-by: default avatarSoheil Hassas Yeganeh <soheil@google.com>
Reviewed-by: default avatarShakeel Butt <shakeelb@google.com>
Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 0defbb0a

include/net/sock.h

+29 −9
Original line number Diff line number Diff line
@@ -1397,22 +1397,48 @@ static inline bool sk_under_memory_pressure(const struct sock *sk) 
	return !!*sk->sk_prot->memory_pressure;

}



static inline long

proto_memory_allocated(const struct proto *prot)

{

	return max(0L, atomic_long_read(prot->memory_allocated));

}



static inline long

sk_memory_allocated(const struct sock *sk)

{

	return atomic_long_read(sk->sk_prot->memory_allocated);

	return proto_memory_allocated(sk->sk_prot);

}



/* 1 MB per cpu, in page units */

#define SK_MEMORY_PCPU_RESERVE (1 << (20 - PAGE_SHIFT))



static inline long

sk_memory_allocated_add(struct sock *sk, int amt)

{

	return atomic_long_add_return(amt, sk->sk_prot->memory_allocated);

	int local_reserve;



	preempt_disable();

	local_reserve = __this_cpu_add_return(*sk->sk_prot->per_cpu_fw_alloc, amt);

	if (local_reserve >= SK_MEMORY_PCPU_RESERVE) {

		__this_cpu_sub(*sk->sk_prot->per_cpu_fw_alloc, local_reserve);

		atomic_long_add(local_reserve, sk->sk_prot->memory_allocated);

	}

	preempt_enable();

	return sk_memory_allocated(sk);

}



static inline void

sk_memory_allocated_sub(struct sock *sk, int amt)

{

	atomic_long_sub(amt, sk->sk_prot->memory_allocated);

	int local_reserve;



	preempt_disable();

	local_reserve = __this_cpu_sub_return(*sk->sk_prot->per_cpu_fw_alloc, amt);

	if (local_reserve <= -SK_MEMORY_PCPU_RESERVE) {

		__this_cpu_sub(*sk->sk_prot->per_cpu_fw_alloc, local_reserve);

		atomic_long_add(local_reserve, sk->sk_prot->memory_allocated);

	}

	preempt_enable();

}



#define SK_ALLOC_PERCPU_COUNTER_BATCH 16
@@ -1441,12 +1467,6 @@ proto_sockets_allocated_sum_positive(struct proto *prot) 
	return percpu_counter_sum_positive(prot->sockets_allocated);

}



static inline long

proto_memory_allocated(struct proto *prot)

{

	return atomic_long_read(prot->memory_allocated);

}



static inline bool

proto_memory_pressure(struct proto *prot)

{