Ubuntu
update-manager package

Poor performance while "Calculating changes"

Bug #852128 reported by Ondřej Buriánek
6
This bug affects 1 person
Affects Status Importance Assigned to Milestone
update-manager (Ubuntu)
Fix Released
Medium
Michael Vogt

Bug Description

I've found performance issue in Distribution Upgrade -> phase Setting new software channels -> Calculating the changes....
Writing in
  * /var/log/dist-upgrade/apt.log
is IMHO done char by char.

When mounting
  * sudo mount -t tmpfs -o size=256M tmpfs /var/log/dist-upgrade
upgrade is much faster.

I found this inconvenience while upgrading Natty to Oneiric with broken dependencies. Upgrade couldn't solve manually installed ia32-libs with nspluginwrapper. When I was watching
  * tail -f /var/log/dist-upgrade/apt.log
characters were added slowly one by one. Writing 42KB log shouldn't take almost a minute :).

Test results committed afterwards:

Conflicted on HDD 1min+
Conflicted on RAM 16sec

Successful on HDD 28sec
Successful on RAM 12sec

ProblemType: Bug
DistroRelease: Ubuntu 11.04
Package: update-manager 1:0.150.3
ProcVersionSignature: Ubuntu 2.6.38-11.49-generic 2.6.38.8
Uname: Linux 2.6.38-11-generic x86_64
NonfreeKernelModules: fglrx
Architecture: amd64
Date: Fri Sep 16 20:39:48 2011
GConfNonDefault:
 /apps/update-manager/check_new_release_ignore=
 /apps/update-manager/first_run=false
 /apps/update-manager/show_details=true
 /apps/update-manager/window_size=(600,600)
InstallationMedia: Ubuntu 10.04 LTS "Lucid Lynx" - Release amd64 (20100427.1)
PackageArchitecture: all
SourcePackage: update-manager
UpgradeStatus: Upgraded to natty on 2011-09-16 (0 days ago)

Revision history for this message
Ondřej Buriánek (zerem) wrote :
Revision history for this message
Steve Langasek (vorlon) wrote :

Per mvo, this is probably in the apt code rather than in update-manager itself, since these are apt logs

affects: update-manager (Ubuntu) → apt (Ubuntu)
Revision history for this message
Michael Vogt (mvo) wrote :

It turns out that u-m was writing the log for this in O_SYNC mode, which is a bit silly as this data is really not important enough to justify this.

Changed in apt (Ubuntu):
assignee: nobody → Michael Vogt (mvo)
status: New → In Progress
importance: Undecided → Medium
affects: apt (Ubuntu) → update-manager (Ubuntu)
Revision history for this message
Launchpad Janitor (janitor) wrote :

This bug was fixed in the package update-manager - 1:0.152.19

---------------
update-manager (1:0.152.19) oneiric; urgency=low

  * DistUpgrade/DistUpgradeCache.py:
    - do not use O_SYNC for the apt.log, its not important enough
      to justify the slowdown (LP: #852128)
 -- Michael Vogt <email address hidden> Wed, 21 Sep 2011 17:55:53 +0200

Changed in update-manager (Ubuntu):
status: In Progress → Fix Released
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