[Bug 947664] Re: Unpacking linux-headers unbelievably slow in Lubuntu Precise (Beta 1)

[Ted]

Anyone experiencing this issue may wish to try these and report back on
what, if any, differences they make:

- Use dpkg's force-unsafe-io.  Put "force-unsafe-io" in
/etc/dpkg/dpkg.cfg.d/unsafe_io

- If using ext4, mount with the "nodelalloc" option.  Either add it in
/etc/fstab or remount with 'mount / -o remount,nodelalloc,<your other
usual options>'

- Use libeatmydata
(https://www.flamingspork.com/projects/libeatmydata/), which is an
LD_PRELOAD library that will disable fsync() and related functions.

FYI, from the man page for dpkg:

              unsafe-io: Do not perform safe I/O operations when
unpacking. Currently this implies not performing file system syncs
before file renames, which is known to cause substantial performance
degradation on some file  systems, unfortunately the ones that require
the safe I/O on the first place due to their unreliable behaviour
causing zero-length files on abrupt system crashes.

              Note: For ext4, the main offender, consider using instead
the mount option nodelalloc, which will fix both the performance
degradation and the data safety issues, the latter by making the file
system not produce zero-length files on abrupt system crashes with any
software not doing syncs before atomic renames.

              Warning: Using this option might improve performance at
the cost of losing data, use with care.

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https://bugs.launchpad.net/bugs/947664

Title:
  Unpacking linux-headers unbelievably slow in Lubuntu Precise (Beta 1)

Status in dpkg:
  New
Status in “dpkg” package in Ubuntu:
  Confirmed

Bug description:
  The below is an example line in an apt-get dist-upgrade which seems to
  take 30 minutes or more on a 2.1GHz CPU (one core of a quad core
  through Virtualbox). I've been looking at it for ages, and even had
  time to log in here and file the bug  - the line is still 'hung'.

  Unpacking linux-headers-3.2.0-18 (from .../linux-
  headers-3.2.0-18_3.2.0-18.28_all.deb)

  Can anyone explain this, or is it a bug in the configuration of
  Lubuntu, Apt-get or something. I read that there was a similarly
  behaving bug to do with dpkg using paranoid file synchronization but
  this length of delay is frankly a bit crazy.

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