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

[Brian J. Murrell]

Hrm.  Something's awry here.  The baseline control package install only
took 27 seconds.  In fact it only takes 10 seconds on subsequent
installations (i.e. after a dpkg -P).  This really did take much much
longer previously.

However, the same operation over NFS on Gige does take 25 minutes.

Over the same NFS with --force-unsafe-io it takes 26 minutes and that's
probably because in analysing with strace, I don't see dpkg doing
anything different per file being installed:

read(9, "./usr/src/linux-headers-3.2.0-24"..., 512) = 512
lstat64("/usr/src/linux-headers-3.2.0-24/arch/alpha/include/asm/gpio.h", 0xbfd1e310) = -1 ENOENT (No such file or directory)
rename("/usr/src/linux-headers-3.2.0-24/arch/alpha/include/asm/gpio.h.dpkg-tmp", "/usr/src/linux-headers-3.2.0-24/arch/alpha/include/asm/gpio.h") = -1 ENOENT (No such file or directory)
rmdir("/usr/src/linux-headers-3.2.0-24/arch/alpha/include/asm/gpio.h.dpkg-tmp") = -1 ENOENT (No such file or directory)
rmdir("/usr/src/linux-headers-3.2.0-24/arch/alpha/include/asm/gpio.h.dpkg-new") = -1 ENOENT (No such file or directory)
open("/usr/src/linux-headers-3.2.0-24/arch/alpha/include/asm/gpio.h.dpkg-new", O_RDWR|O_CREAT|O_EXCL|O_LARGEFILE, 0) = 10
read(9, "/*\n * Generic GPIO API implement"..., 1196) = 1196
write(10, "/*\n * Generic GPIO API implement"..., 1196) = 1196
read(9, "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"..., 340) = 340
sync_file_range(0xa, 0, 0, 0)           = 0
fchown32(10, 0, 0)                      = 0
fchmod(10, 0644)                        = 0
close(10)                               = 0
utimes("/usr/src/linux-headers-3.2.0-24/arch/alpha/include/asm/gpio.h.dpkg-new", {{1338377227, 0}, {1325721344, 0}}) = 0

So it seems there is still a sync being done after each file is written,
even with --force-unsafe-io.

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

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

Status in “dpkg” package in Ubuntu:
  Incomplete

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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