Bug#700633: Debootstrap is very slow. Please use eatmydata to fix this.

[Bob Proulx <bob@proulx.com>]

Phillip Susi wrote:
> After patching debootstrap to add eatmydata to the required list,
> and activate it during the second stage install, the time to
> construct the chroot dropped from 10m to 2m. This should also make
> installing new systems MUCH faster.

I have also been suffering with the much slower dpkg on Sid.  Today I
performed a test of a default debootstrap chroot and had this
benchmark data.  I am using a local full mirror so that network
performance is not significant in the measurement.  This is using the
stock Sid version of everything up to date as of today operating on an
ext3 filesystem.

  # time debootstrap wheezy testinstall http://localmirror/ftp.us.debian.org/debian
  ...
  real    2m58.577s
  user    0m49.639s
  sys     0m8.749s

And then using the patched debootstrap script Phillip Susi suggested I
get this result:

  # time debootstrap wheezy testinstall http://localmirror/ftp.us.debian.org/debian
  ...
  real    1m17.680s
  user    0m49.879s
  sys     0m7.988s

Wall clock time is more than 2x faster for me when avoiding the
unnecessary fsync() calls.  Ideally I would like to see dpkg handle
this issue.  But since that doesn't seem to be happening it would be
nice if the rest of the ecosystem could work around it.

Here is the same test again on an ext4 filesystem on the same system
and the stock scripts.

  # time debootstrap wheezy testinstall http://localmirror/ftp.us.debian.org/debian
  ...
  real    2m55.402s
  user    0m52.107s
  sys     0m7.888s

And again with the eatmydata patched script:

  # time debootstrap wheezy testinstall http://localmirror/ftp.us.debian.org/debian
  ...
  real    1m4.819s
  user    0m48.455s
  sys     0m6.752s

That is 2.7x faster on ext4.

Bob