From mboxrd@z Thu Jan 1 00:00:00 1970 From: Manavalan Krishnan Subject: Re: Large file copy to NFS mounted directory causes delay in other application packets Date: Wed, 9 Nov 2011 00:13:09 -0800 (PST) Message-ID: <1320826389.47194.YahooMailNeo@web160716.mail.bf1.yahoo.com> References: <1320816503.73813.YahooMailNeo@web160718.mail.bf1.yahoo.com> <1320819875.26025.48.camel@edumazet-laptop> Reply-To: Manavalan Krishnan Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: linux-kernel@vger.kernel.org, netdev To: Eric Dumazet , "linux-kernel@vger.kernel.org" Return-path: Received: from nm22.bullet.mail.bf1.yahoo.com ([98.139.212.181]:22131 "HELO nm22.bullet.mail.bf1.yahoo.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1755551Ab1KIINL convert rfc822-to-8bit (ORCPT ); Wed, 9 Nov 2011 03:13:11 -0500 In-Reply-To: <1320819875.26025.48.camel@edumazet-laptop> Sender: netdev-owner@vger.kernel.org List-ID: (1) NFS is using TCP (2) yes eth0 is dedicated to heartbeat and eth1 is dedicated to NFS (3) I notice the following at the system where file copy is occuring The kernel Recv-Q of the heartbeat application socket grows but not del= ivered to the socket recv call.=A0 Here is the netstat output. Proto=A0 Recv-Q=A0 Send-Q=A0=A0 Local Address=A0=A0=A0=A0=A0=A0=A0=A0 F= oreign Address udp=A0=A0=A0 11522=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 0=A0 *:= 23435=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0=A0 *:* As soon as I stop the file transfer, the socket recv call receives the = packets and Recv-Q goes 0. (4) The server has 4 cpu cores and 25G RAM ________________________________ =46rom: Eric Dumazet To: Manavalan Krishnan Cc: "linux-kernel@vger.kernel.org" ; netd= ev Sent: Tuesday, November 8, 2011 10:24 PM Subject: Re: Large file copy to NFS mounted directory causes delay in o= ther application packets Le mardi 08 novembre 2011 =E0 21:28 -0800, Manavalan Krishnan a =E9crit= : > Hi All >=20 > I have two systems with two network interfaces each(eth0 and eth1). I > am running linux-HA (heartbeat deamon) on both the systems and they > use eth0 for exchanging heartbeats. I have NFS mounted directory in > one system and the NFS client uses the interface eth1.=20 >=20 > I try to copy a large file to NFS mounted directory. But the heartbea= t > daemons misses the heartbeat packets from peers while copy is under > progress. I did tcpdump and found that the heartbeat packets are > delayed for few seconds before sent out on eth0. When I stop the file > copy, the heartbeats are delivered properly. It seems linux kernel > somehow giving priority for NFS packets(generated from the file copy) > over other application packets. >=20 > Any thoughts on this behavior? Is there any way we can avoid this so > that application packets get equal chance while large file copy to NF= S > mounted directory under progress? >=20 CC netdev 1) Is your NFS using UDP or TCP ? 2) Is your eth0 dedicated to heartbeats and eth1 to NFS traffic ? 3) How do you know heartbeats are delayed ? 4) Is your server CPU bounded ? Thanks -- To unsubscribe from this list: send the line "unsubscribe linux-kernel"= in the body of a message to majordomo@vger.kernel.org More majordomo info at=A0 http://vger.kernel.org/majordomo-info.html Please read the FAQ at=A0 http://www.tux.org/lkml/