I am not sure which package sould be responsible for that, probably either xorg-server or lightdm.
Previously, up to raring, when you left the computer alone while it was showing the login screen (lightdm in my case), the monitor would turn off after five or ten minutes. Since upgrade from raring to saucy, monitor stays on indefinitely, after boot and after logout likewise. This is on two machines, one a notebook with Intel graphics, another desktop with Radeon using open source driver.
I guess maybe setting up DPMS got broken in the process of migration to Mir and back to xorg.
---
.tmp.unity.support.test.0:
ApportVersion: 2.12.5-0ubuntu2.1
Architecture: amd64
CompizPlugins: [core,composite,opengl,compiztoolbox,decor,vpswitch,snap,mousepoll,resize,place,move,wall,grid,regex,imgpng,session,gnomecompat,animation,fade,unitymtgrabhandles,workarounds,scale,expo,ezoom,unityshell]
CompositorRunning: compiz
CompositorUnredirectDriverBlacklist: '(nouveau|Intel).*Mesa 8.0'
CompositorUnredirectFSW: true
DistUpgraded: 2013-10-26 13:27:24,614 DEBUG enabling apt cron job
DistroCodename: saucy
DistroRelease: Ubuntu 13.10
DistroVariant: ubuntu
ExtraDebuggingInterest: Yes
GraphicsCard:
Advanced Micro Devices, Inc. [AMD/ATI] Trinity [Radeon HD 7660D] [1002:9901] (prog-if 00 [VGA controller])
Subsystem: ASUSTeK Computer Inc. Device [1043:8526]
MachineType: System manufacturer System Product Name
MarkForUpload: True
Package: xorg-server (not installed)
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-3.11.0-13-generic root=UUID=72283a55-e0f7-4036-af5e-be1174497a35 ro quiet splash vt.handoff=7
ProcVersionSignature: Ubuntu 3.11.0-13.20-generic 3.11.6
Tags: saucy ubuntu compiz-0.9
Uname: Linux 3.11.0-13-generic x86_64
UpgradeStatus: Upgraded to saucy on 2013-10-26 (2 days ago)
UserGroups: adm admin audio cdrom dialout lpadmin plugdev sambashare video
dmi.bios.date: 10/09/2012
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: 5105
dmi.board.asset.tag: To be filled by O.E.M.
dmi.board.name: F2A85-M LE
dmi.board.vendor: ASUSTeK COMPUTER INC.
dmi.board.version: Rev X.0x
dmi.chassis.asset.tag: Asset-1234567890
dmi.chassis.type: 3
dmi.chassis.vendor: Chassis Manufacture
dmi.chassis.version: Chassis Version
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvr5105:bd10/09/2012:svnSystemmanufacturer:pnSystemProductName:pvrSystemVersion:rvnASUSTeKCOMPUTERINC.:rnF2A85-MLE:rvrRevX.0x:cvnChassisManufacture:ct3:cvrChassisVersion:
dmi.product.name: System Product Name
dmi.product.version: System Version
dmi.sys.vendor: System manufacturer
version.compiz: compiz 1:0.9.10+13.10.20131011-0ubuntu1
version.ia32-libs: ia32-libs N/A
version.libdrm2: libdrm2 2.4.46-1
version.libgl1-mesa-dri: libgl1-mesa-dri 9.2.1-1ubuntu3
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx 9.2.1-1ubuntu3
version.xserver-xorg-core: xserver-xorg-core 2:1.14.3-3ubuntu2
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.7.3-0ubuntu3.1
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:7.2.0-0ubuntu10
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.904-0ubuntu2
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.9-2ubuntu1
xserver.bootTime: Mon Oct 28 12:00:05 2013
xserver.configfile: /etc/X11/xorg.conf
xserver.errors:
Failed to load /usr/lib/xorg/modules/drivers/fglrx_drv.so: /usr/lib/xorg/modules/drivers/fglrx_drv.so: cannot open shared object file: No such file or directory
Failed to load module "fglrx" (loader failed, 7)
Failed to load /usr/lib/xorg/modules/drivers/fglrx_drv.so: /usr/lib/xorg/modules/drivers/fglrx_drv.so: cannot open shared object file: No such file or directory
Failed to load module "fglrx" (loader failed, 7)
xserver.logfile: /var/log/Xorg.0.log
xserver.version: 2:1.14.3-3ubuntu2
xserver.video_driver: radeon
Let's target xorg-server to start with. In addition to the logs from xorg-server, please upload the logs contained in /var/log/lightdm. Collecting the xorg-server logs should be as easy as running "apport-collect 1245474".