[Bug 585092] Re: tmpfs umount slowdown

[Brian Bloniarz]

apport information

** Tags added: apport-collected

** Description changed:

  On a fresh lucid install, an unmount of an empty tmpfs mount is quite
  slow:
  
  # mkdir -p /tmp/test; mount -t tmpfs nodev /tmp/test; time umount /tmp/test
  real    0m0.318s
  user    0m0.000s
  sys 0m0.020s
  
  If there is pending I/O on any other filesystem, it can be even slower:
  # dd if=/dev/zero of=/tmp/testfile bs=1024 count=1024
  # mkdir -p /tmp/test; mount -t tmpfs nodev /tmp/test; time umount /tmp/test
  real    0m8.270s
  user    0m0.000s
  sys 0m0.010s
  
  This is a regression from previous versions, e.g. on hardy:
  # uname -r
  2.6.24-19-generic
  # mkdir -p /tmp/test; mount -t tmpfs nodev /tmp/test; time umount /tmp/test
  real    0m0.001s
  user    0m0.000s
  sys 0m0.000s
  
- The root cause is the workaround patch which fixed bug
- https://bugs.launchpad.net/ubuntu/+source/linux/+bug/543617. It syncs
- all filesystems when umount is called, not just the involved filesystem,
- and applies to unmount of non-ext4 FSs. I've verified that the problem
- goes away with that patch reverted.
+ The root cause is the workaround patch which fixed bug https://bugs.launchpad.net/ubuntu/+source/linux/+bug/543617. It syncs all filesystems when umount is called, not just the involved filesystem, and applies to unmount of non-ext4 FSs. I've verified that the problem goes away with that patch reverted.
+ --- 
+ AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.21.
+ Architecture: amd64
+ AudioDevicesInUse:
+  USER        PID ACCESS COMMAND
+  /dev/snd/controlC0:  ubuntu     2819 F.... pulseaudio
+ CRDA: Error: [Errno 2] No such file or directory
+ Card0.Amixer.info:
+  Card hw:0 'NVidia'/'HDA NVidia at 0xfe024000 irq 22'
+    Mixer name	: 'Realtek ALC882'
+    Components	: 'HDA:10ec0882,10eca201,00100101'
+    Controls      : 39
+    Simple ctrls  : 21
+ DistroRelease: Ubuntu 10.04
+ IwConfig:
+  lo        no wireless extensions.
+  
+  eth0      no wireless extensions.
+ LiveMediaBuild: Ubuntu 10.04 LTS "Lucid Lynx" - Release amd64 (20100429)
+ Lsusb:
+  Bus 002 Device 007: ID 413c:2106 Dell Computer Corp. 
+  Bus 002 Device 006: ID 413c:3200 Dell Computer Corp. Mouse
+  Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub
+  Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
+ MachineType: Shuttle Inc SN27V10
+ Package: linux (not installed)
+ ProcCmdLine: BOOT_IMAGE=/casper/vmlinuz file=/cdrom/preseed/hostname.seed boot=casper initrd=/casper/initrd.lz quiet splash -- maybe-ubiquity
+ ProcEnviron:
+  PATH=(custom, no user)
+  LANG=en_US.UTF-8
+  SHELL=/bin/bash
+ ProcVersionSignature: Ubuntu 2.6.32-21.32-generic 2.6.32.11+drm33.2
+ Regression: Yes
+ RelatedPackageVersions: linux-firmware 1.34
+ Reproducible: Yes
+ RfKill:
+  
+ Tags: lucid filesystem regression-release needs-upstream-testing
+ Uname: Linux 2.6.32-21-generic x86_64
+ UserGroups:
+  
+ dmi.bios.date: 06/27/2007
+ dmi.bios.vendor: Phoenix Technologies, LTD
+ dmi.bios.version: 6.00 PG
+ dmi.board.name: FN27V10
+ dmi.board.vendor: Shuttle Inc
+ dmi.chassis.type: 3
+ dmi.modalias: dmi:bvnPhoenixTechnologies,LTD:bvr6.00PG:bd06/27/2007:svnShuttleInc:pnSN27V10:pvr:rvnShuttleInc:rnFN27V10:rvr:cvn:ct3:cvr:
+ dmi.product.name: SN27V10
+ dmi.sys.vendor: Shuttle Inc

** Attachment added: "AlsaDevices.txt"
   http://launchpadlibrarian.net/49091807/AlsaDevices.txt

-- 
tmpfs umount slowdown
https://bugs.launchpad.net/bugs/585092
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