[Bug 1398434] Re: e4defrag has fatal CPU performance bottleneck

[Theodore Ts'o]

Please strace the e4defrag process to see if it is spinning in userspace
or in the kernel.    If it is spinning in the kernel, then it's a kernel
bug, not an e2fsrpogs problem.  And since you're using a non-Ubuntu
kernel, you'll need to take this to the upstream linux-ext4 mailing
list.

If it turns out to be a case of spinning in the kernel,  what we'll want
to know is whether you can easily reproduce the problem, and if so,
whether you can give us a kernel stack trace by using magic-sysrq-l and
magic-sysrq-t.

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https://bugs.launchpad.net/bugs/1398434

Title:
  e4defrag has fatal CPU performance bottleneck

Status in e2fsprogs package in Ubuntu:
  New

Bug description:
  During defragmentation of a 5 TB ext4 filesystem with one 600 GB file
  with current value of 300000 and optimal value of 300 shown by
  `e4defrag -c`, `e4defrag' seems to suffer from a huge CPU performance
  bottleneck. Over hours only one CPU core is used (-> no
  parallelization) and there's almost no I/O during that time <1 % of
  the underlying device's capabilities.

  ProblemType: Bug
  DistroRelease: Ubuntu 14.10
  Package: e2fsprogs 1.42.10-1.1ubuntu1
  Uname: Linux 3.17.4-031704-generic x86_64
  ApportVersion: 2.14.7-0ubuntu8
  Architecture: amd64
  CurrentDesktop: Unity
  Date: Tue Dec  2 16:29:12 2014
  SourcePackage: e2fsprogs
  UpgradeStatus: No upgrade log present (probably fresh install)

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