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net: set SK_MEM_QUANTUM to 4096

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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: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2016-10-31 13:32:55 -07:00 committed by David S. Miller
parent a13925a46e
commit bd68a2a854
1 changed files with 17 additions and 6 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

23
include/net/sock.h
View file

@ -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;