Archive for June, 2009

LDAP and its many uses

Friday, June 19th, 2009

There is a nice article on Single-Sign-On and LDAP in the Journal and although it is not new the man writing it has clearly spent some time finding novel (read: whack) uses for catalogue services.

Myself, on the other hand, I’ve been finding novel ways to break OpenLDAP. My 35-hour stint on Thursday set up more Active Directory-integrating workaround setups of the Slap Daemon than you can shake a bloody large stick at, including but not limited to The Inverted Translucent Reverse Meta Tree, where we do a slapo-translucent overlay in one slapd and a plain slapd database in the second slapd, then slapd-meta the sAMAccountName into uid and remap the suffixes in a third slapd process. Yep, that’s four separate catalogues to solve one application problem.

Don’t. Ask. Why.

The upshot is that you should stay the hell away from the slapd rewrite module as it will core, that the translucent overlay is magnificent at making very plain ldapsearches (objectclass=*) return no objects or fail, that slapd-meta is a very cool backend to do remapping suffixes, attributes and your mom, that your application should never have to write to a read-only Active Directory tree, and that simplicity is instrumental in not going mental.

Unfortunately, simple solutions to complicated problems are rather hard to come by.

PS. The problems I was trying to fix all came out of one single application bug and my attempts to work around it :-P

Xorg is a steaming pile of gonzales so turn on your UXA

Sunday, June 7th, 2009

Hei folks,

if you have a newer Intel or ATI gfx card, and you’re running a suitably dishy distribution (Ubuntu Jaunty maybe, xorg 7.4, kernels 2.6.27 and up perhaps?) maybe you’ve noticed how sluggish and slow Xorg is. Sometimes it’ll be a dick and eat heaps of your RAM, and maybe hog 98% of your CPU time for no damn raisins.

Furthermore, that sleek graphics card seems to be causing loads of garbage rendering – what gives? I wish I could show you some screenshots but honestly, I don’t really wanna see that shit again, so here’s to not reproducing it. Instead, why don’t you do like I do and enable UXA? Edit your /etc/X11/xorg.conf file and add
Option "AccelMethod" "uxa" to your acting Device section like so:

Section "Device"
   Identifier    "integrated"
   Driver "intel"
      Option "AccelMethod" "uxa"
      Option "RenderAccel" "on"
      Option "PageFlip" "on"
EndSection

Now logout and back into X again, restart GDM, KDM or whatever and whoop de doo your /var/log/Xorg.0.log should say something like:

(**) intel(0): Using UXA for acceleration
[... snip irrelevant shit ...]
(II) intel(0): [DRI2] Setup complete
[... more irrelevant crap ...]
(II) UXA(0): Driver registered support for the following operations:
(II)         solid
(II)         copy
(II)         composite (RENDER acceleration)
[... further noise ...]
(II) intel(0): direct rendering: DRI2 Enabled

Also, windows should draw/move/resize snappier and there should be much rejoicing. If everything went all right that is.

Note that my glxgears performance dropped from 1300fps (w/xcompmgr) down to 660fps (xcompmgr) and 994fps (no composition manager) so there seems to be a tradeoff here, but I really really prefer my gooey windows snappy, artifact-free and less crash-prone. maybe.

K out