Direct rendering only works for one user, so Compiz runs slowly in a multiple user system

Bug #161106 reported by peegee on 2007-11-09
6
Affects Status Importance Assigned to Milestone
X.Org X server
New
Undecided
Unassigned
xorg (Ubuntu)
Wishlist
Unassigned

Bug Description

In a computer where several users are logged in simultaneously, only one user is able to enjoy the benefits of hardware accelerated 3D graphics. This can be confirmed by running the command "glxinfo | grep 'direct rendering'" for each user prior to switching virtual screens, either through the fast user switcher applet or by pressing CTRL-ALT-F# [#=number of the virtual screen]. Direct rendering ("direct rendering: Yes) only works for one user, in general, the first one to log in. As a result of this, Compiz runs fast only for that user. The other users have to make do with slow indirect rendering.

The workaround of having the "DRI-enabled" user log out to free the needed system resource is not ideal, given the fact that Linux is supposed to be a multiple user operating system.

Further information can be found in a discussion at the DRI-Users mailing list. An archive of the thread titled "Only one user has DRI" can be found at http://marc.info/?t=119413177000001&r=1&w=2

Bryce Harrington (bryce) on 2008-01-22
Changed in xorg:
importance: Undecided → Wishlist
status: New → Confirmed
Andrew Oakley (andrew-aoakley) wrote :

In Hardy Alpha 3 with all updates to date (2008-01-24), generally the first to log in gets Compiz and subsequent users do not, even if they have got Advanced Desktop Effects enabled by default.

There is no warning, most users will find this counter-intuitive and confusing. Because Switch Users is most likely to be used by families sharing a computer, the users who encounter this bug will generally not be very experienced. They may report duplicate bugs or clog up support forums.

Therefore I have added two wishlists related to this bug:

Bug #185586 - Users should be warned when switching users disables Compiz

Bug #185599 - Missing option to disable Fast User Switching

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