[PATCH 3.16 325/370] net: fix sk_mem_reclaim_partial()

Ben Hutchings
2017-03-10T13:29:02Z

From: Eric Dumazet <edumazet@google.com>

commit 1a24e04e4b50939daa3041682b38b82c896ca438 upstream.

sk_mem_reclaim_partial() goal is to ensure each socket has
one SK_MEM_QUANTUM forward allocation. This is needed both for
performance and better handling of memory pressure situations in
follow up patches.

SK_MEM_QUANTUM is currently a page, but might be reduced to 4096 bytes
as some arches have 64KB pages.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
include/net/sock.h | 6 +++---
net/core/sock.c | 9 +++++----
2 files changed, 8 insertions(+), 7 deletions(-)

--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -1411,7 +1411,7 @@ static inline struct inode *SOCK_INODE(s
* 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)
@@ -1452,7 +1452,7 @@ static inline void sk_mem_reclaim(struct
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)
@@ -1460,7 +1460,7 @@ static inline void sk_mem_reclaim_partia
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)
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -2125,12 +2125,13 @@ 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)))