From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: [PATCH v2 net-next] net: set SK_MEM_QUANTUM to 4096 Date: Mon, 31 Oct 2016 13:32:55 -0700 Message-ID: <1477945975.7065.317.camel@edumazet-glaptop3.roam.corp.google.com> References: <1477940320.7065.312.camel@edumazet-glaptop3.roam.corp.google.com> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: netdev , Neal Cardwell , Yuchung Cheng To: David Miller Return-path: Received: from mail-pf0-f195.google.com ([209.85.192.195]:34430 "EHLO mail-pf0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S946507AbcJaUc6 (ORCPT ); Mon, 31 Oct 2016 16:32:58 -0400 Received: by mail-pf0-f195.google.com with SMTP id y68so3714986pfb.1 for ; Mon, 31 Oct 2016 13:32:57 -0700 (PDT) In-Reply-To: <1477940320.7065.312.camel@edumazet-glaptop3.roam.corp.google.com> Sender: netdev-owner@vger.kernel.org List-ID: From: Eric Dumazet 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 --- include/net/sock.h | 23 +++++++++++++++++------ 1 file changed, 17 insertions(+), 6 deletions(-) diff --git a/include/net/sock.h b/include/net/sock.h index f13ac87a8015cb18c5d3fe5fdcf2d6a0592428f4..d904d1835e06c970fea958c048d927137171477f 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -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;