Commit bd68a2a8 authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

net: set SK_MEM_QUANTUM to 4096 



Systems with large pages (64KB pages for example) do not always have
huge quantity of memory.

A big SK_MEM_QUANTUM value leads to fewer interactions with the
global counters (like tcp_memory_allocated) but might trigger
memory pressure much faster, giving suboptimal TCP performance
since windows are lowered to ridiculous values.

Note that sysctl_mem units being in pages and in ABI, we also need
to change sk_prot_mem_limits() accordingly.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent a13925a4

include/net/sock.h

+17 −6
Original line number Diff line number Diff line
@@ -1162,11 +1162,6 @@ static inline void sk_enter_memory_pressure(struct sock *sk) 
	sk->sk_prot->enter_memory_pressure(sk);

}



static inline long sk_prot_mem_limits(const struct sock *sk, int index)

{

	return sk->sk_prot->sysctl_mem[index];

}



static inline long

sk_memory_allocated(const struct sock *sk)

{
@@ -1281,11 +1276,27 @@ int __sk_mem_schedule(struct sock *sk, int size, int kind); 
void __sk_mem_reduce_allocated(struct sock *sk, int amount);

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



#define SK_MEM_QUANTUM ((int)PAGE_SIZE)

/* We used to have PAGE_SIZE here, but systems with 64KB pages

 * do not necessarily have 16x time more memory than 4KB ones.

 */

#define SK_MEM_QUANTUM 4096

#define SK_MEM_QUANTUM_SHIFT ilog2(SK_MEM_QUANTUM)

#define SK_MEM_SEND	0

#define SK_MEM_RECV	1



/* sysctl_mem values are in pages, we convert them in SK_MEM_QUANTUM units */

static inline long sk_prot_mem_limits(const struct sock *sk, int index)

{

	long val = sk->sk_prot->sysctl_mem[index];



#if PAGE_SIZE > SK_MEM_QUANTUM

	val <<= PAGE_SHIFT - SK_MEM_QUANTUM_SHIFT;

#elif PAGE_SIZE < SK_MEM_QUANTUM

	val >>= SK_MEM_QUANTUM_SHIFT - PAGE_SHIFT;

#endif

	return val;

}



static inline int sk_mem_pages(int amt)

{

	return (amt + SK_MEM_QUANTUM - 1) >> SK_MEM_QUANTUM_SHIFT;

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