From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: [PATCH net-next] net: set SK_MEM_QUANTUM to 4096 Date: Mon, 31 Oct 2016 11:58:40 -0700 Message-ID: <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]:36720 "EHLO mail-pf0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S945669AbcJaS6m (ORCPT ); Mon, 31 Oct 2016 14:58:42 -0400 Received: by mail-pf0-f195.google.com with SMTP id n85so9406205pfi.3 for ; Mon, 31 Oct 2016 11:58:42 -0700 (PDT) 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, thus suboptimal TCP performance since windows are lowered to ridiculous values. Signed-off-by: Eric Dumazet --- include/net/sock.h | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/include/net/sock.h b/include/net/sock.h index f13ac87a8015cb18c5d3fe5fdcf2d6a0592428f4..d3409bb514e7f08b9cf183b7405d876bec18d732 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -1281,7 +1281,10 @@ 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