From mboxrd@z Thu Jan  1 00:00:00 1970
From: Eric Dumazet <eric.dumazet@gmail.com>
Subject: Re: Large file copy to NFS mounted directory causes delay in other
 application packets
Date: Wed, 09 Nov 2011 09:59:09 +0100
Message-ID: <1320829149.2315.6.camel@edumazet-HP-Compaq-6005-Pro-SFF-PC>
References: <1320816503.73813.YahooMailNeo@web160718.mail.bf1.yahoo.com>
	 <1320819875.26025.48.camel@edumazet-laptop>
	 <1320826389.47194.YahooMailNeo@web160716.mail.bf1.yahoo.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: QUOTED-PRINTABLE
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	netdev <netdev@vger.kernel.org>
To: Manavalan Krishnan <manavalan_k@yahoo.com>
Return-path: <linux-kernel-owner@vger.kernel.org>
In-Reply-To: <1320826389.47194.YahooMailNeo@web160716.mail.bf1.yahoo.com>
Sender: linux-kernel-owner@vger.kernel.org
List-Id: netdev.vger.kernel.org

Please dont top post on these lists, thanks.

Le mercredi 09 novembre 2011 =C3=A0 00:13 -0800, Manavalan Krishnan a =C3=
=A9crit :
> (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
>=20
> The kernel Recv-Q of the heartbeat application socket grows but not d=
elivered to the socket recv call.=20
> Here is the netstat output.
>=20
> Proto  Recv-Q  Send-Q   Local Address         Foreign Address
>=20
> udp    11522                0  *:23435                     *:*
>=20

OK so the sending side is OK : The delay is at receiver side.

Note that since netstat shows receive queue has some skbs, it should be
available to heartbeat daemon immediately.

> As soon as I stop the file transfer, the socket recv call receives th=
e packets and Recv-Q goes 0.
> (4) The server has 4 cpu cores and 25G RAM
>=20

1) How many nfsd threads are running ?
   grep th /proc/net/rpc/nfsd

2) WHat kind of NIC do you use ?
   lsmod , lspci

3) Hmm, are IRQ to eth0/eth1 handled by same cpu ?
  grep eth /proc/interrupts

4) You could try to cpu affine all nfsd to cpu0,cpu1,cpu2  and heartbea=
t
daemon to cpu3.
   man taskset

5) You could 'strace -ttt' heartbeat daemon to check if it is not
blocked on some local disk access (it competes with all nfsd threads)