nfsd creates high load on 3.x kernels

[Karsten Suehring]

Adding my debug information as a separate bug report as suggested by apport. It's related to Bug #879334 and Bug #1006446

Symptoms: accessing a NFS network share on Ubuntu 12.04 causes high load on the server. A single file write on a single client causes the server to go up to 40% system load. Several clients accessing the share make the server unusable.

The problem can be easily reproduced as described in Bug #1006446. I tested with upstream Debian in my virtual machines: Squeeze has a server load of 7-10% (which seems high, but might be related to using a VM). When upgraded to Debian Wheezy the load goes up to 40% as in Ubuntu 12.04. When I boot the old 2.6 kernel from Squeeze, the load goes back to the original values.

On Ubuntu 12.04 I tried several share and mount options. The only change that showed an effect was mounting with -o proto=udp which reduced the load to around 15% which is still more than the old kernel, but much better than the 40% with tcp.

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: linux-image (not installed)
ProcVersionSignature: Ubuntu 3.2.0-32.51-generic 3.2.30
Uname: Linux 3.2.0-32-generic x86_64
AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.24.
AplayDevices: Error: [Errno 2] No such file or directory
ApportVersion: 2.0.1-0ubuntu14
Architecture: amd64
ArecordDevices: Error: [Errno 2] No such file or directory
AudioDevicesInUse: Error: command ['fuser', '-v', '/dev/snd/by-path', '/dev/snd/controlC0', '/dev/snd/pcmC0D0c', '/dev/snd/pcmC0D0p', '/dev/snd/pcmC0D1c', '/dev/snd/seq', '/dev/snd/timer'] failed with exit code 1:
CRDA: Error: [Errno 2] No such file or directory
Card0.Amixer.info: Error: [Errno 2] No such file or directory
Card0.Amixer.values: Error: [Errno 2] No such file or directory
CurrentDmesg:
 [ 19.184082] eth0: no IPv6 routers present
 [ 98.594102] atkbd serio0: Spurious NAK on isa0060/serio0. Some program might be trying access hardware directly.
Date: Sun Nov 11 12:23:35 2012
HibernationDevice: RESUME=UUID=a004b988-8ee3-4834-9ae3-1a951102e805
InstallationMedia: Ubuntu-Server 12.04.1 LTS "Precise Pangolin" - Release amd64 (20120817.3)
IwConfig:
 lo no wireless extensions.

 eth0 no wireless extensions.
Lsusb:
 Bus 001 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
 Bus 001 Device 002: ID 80ee:0021 VirtualBox USB Tablet
MachineType: innotek GmbH VirtualBox
ProcEnviron:
 TERM=linux
 LANG=en_US.UTF-8
 SHELL=/bin/bash
ProcFB: 0 VESA VGA
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.2.0-32-generic root=UUID=be5ccd34-f906-47e2-98f2-3335f04389c8 ro
RelatedPackageVersions:
 linux-restricted-modules-3.2.0-32-generic N/A
 linux-backports-modules-3.2.0-32-generic N/A
 linux-firmware 1.79.1
RfKill: Error: [Errno 2] No such file or directory
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 12/01/2006
dmi.bios.vendor: innotek GmbH
dmi.bios.version: VirtualBox
dmi.board.name: VirtualBox
dmi.board.vendor: Oracle Corporation
dmi.board.version: 1.2
dmi.chassis.type: 1
dmi.chassis.vendor: Oracle Corporation
dmi.modalias: dmi:bvninnotekGmbH:bvrVirtualBox:bd12/01/2006:svninnotekGmbH:pnVirtualBox:pvr1.2:rvnOracleCorporation:rnVirtualBox:rvr1.2:cvnOracleCorporation:ct1:cvr:
dmi.product.name: VirtualBox
dmi.product.version: 1.2
dmi.sys.vendor: innotek GmbH

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.