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net: implement per-cpu reserves for memory_allocated

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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: Eric Dumazet <[email protected]>
Acked-by: Soheil Hassas Yeganeh <[email protected]>
Reviewed-by: Shakeel Butt <[email protected]>
Signed-off-by: Jakub Kicinski <[email protected]>
This commit is contained in:
Eric Dumazet authored and Jakub Kicinski committed 2022-06-10 16:21:26 -07:00
1 parent 0defbb0af7
commit 3cd3399dd7
1 file changed
+29 -9
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include/net/sock.h
+29 -9
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@@ -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)
{