From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH 1/3] [UDP]: add udp_mem, udp_rmem_min and udp_wmem_min Date: Thu, 10 Jan 2008 22:00:15 -0800 (PST) Message-ID: <20080110.220015.118987509.davem@davemloft.net> References: <4778AE48.1040701@cosmosbay.com> <20071231.041342.101160102.davem@davemloft.net> <4778FFE2.9090008@cosmosbay.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: haoki@redhat.com, herbert@gondor.apana.org.au, netdev@vger.kernel.org, tyasui@redhat.com, mhiramat@redhat.com, satoshi.oshima.fk@hitachi.com, billfink@mindspring.com, andi@firstfloor.org, johnpol@2ka.mipt.ru, shemminger@linux-foundation.org, yoshfuji@linux-ipv6.org, yumiko.sugita.yf@hitachi.com To: dada1@cosmosbay.com Return-path: Received: from 74-93-104-97-Washington.hfc.comcastbusiness.net ([74.93.104.97]:47620 "EHLO sunset.davemloft.net" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1750760AbYAKGAQ (ORCPT ); Fri, 11 Jan 2008 01:00:16 -0500 In-Reply-To: <4778FFE2.9090008@cosmosbay.com> Sender: netdev-owner@vger.kernel.org List-ID: From: Eric Dumazet Date: Mon, 31 Dec 2007 15:42:42 +0100 > Maybe we need to introduce some mechanism to let sk_forward between 0 and > SK_MEM_QUANTUM (inclusive). > > static inline void sk_mem_reclaim_overpage(struct sock *sk) > { > if (sk->sk_forward_alloc > SK_MEM_QUANTUM) { > __sk_mem_reclaim(sk); > } > } > > and use sk_mem_reclaim_overpage() instead of sk_mem_reclaim() in > tcp_delack_timer() ? This makes a lot of sense to me, it is definitely doing the wrong thing here for the load you describe. I've applied the following to net-2.6.25 and I am definitely willing to put this into 2.6.24 and -stable if you think that's worthwhile too. [TCP]: Do not purge sk_forward_alloc entirely in tcp_delack_timer(). Otherwise we beat heavily on the global tcp_memory atomics when all of the sockets in the system are slowly sending perioding packet clumps. Noticed and suggested by Eric Dumazet. Signed-off-by: David S. Miller --- include/net/sock.h | 8 ++++++++ net/ipv4/tcp_timer.c | 2 +- 2 files changed, 9 insertions(+), 1 deletions(-) diff --git a/include/net/sock.h b/include/net/sock.h index 89e04e4..d24b826 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -759,6 +759,14 @@ static inline void sk_mem_reclaim(struct sock *sk) __sk_mem_reclaim(sk); } +static inline void sk_mem_reclaim_partial(struct sock *sk) +{ + if (!sk_has_account(sk)) + return; + if (sk->sk_forward_alloc > SK_MEM_QUANTUM) + __sk_mem_reclaim(sk); +} + static inline void sk_mem_charge(struct sock *sk, int size) { if (!sk_has_account(sk)) diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c index 17931be..803d758 100644 --- a/net/ipv4/tcp_timer.c +++ b/net/ipv4/tcp_timer.c @@ -186,7 +186,7 @@ static void tcp_delack_timer(unsigned long data) goto out_unlock; } - sk_mem_reclaim(sk); + sk_mem_reclaim_partial(sk); if (sk->sk_state == TCP_CLOSE || !(icsk->icsk_ack.pending & ICSK_ACK_TIMER)) goto out; -- 1.5.4.rc2.84.gf85fd