New handling of privates [was: Re: xf86-video-intel 2.5 release planning]
ewalsh at tycho.nsa.gov
Fri Aug 1 15:21:47 PDT 2008
Keith Packard wrote:
> On Fri, 2008-08-01 at 13:56 -0400, Eamon Walsh wrote:
>> Yes, this consolidation should be done. I also have the OK from Peter
>> to remove some DIX-level keys associated with the MPX merge. And
>> lately, a lot of code has been dropped from master which has cut down on
>> the number of keys.
> The private indicies should be allocated per object-type instead of
> globally; that way you'd only deal with the number of privates that
> could be instantiated on a particular object.
> That's the way it used to work.
The per-object-type support was dropped because under the current
linked-list implementation it isn't necessary; each object's list
contains only the privates that have been referenced.
Going back to a fixed array will cause a "sparse" situation with unused
spaces in the array (4 bytes per key-not-in-use per object). Tomas has
noted that it's possible to combine keys in many cases, so that instead
of three keys for separate object types there would only be one. But
yeah, I guess with millions or billions or whatever of pixmaps, the
wasted space could add up.
I think I know how to add per-object-type support back without breaking
things. Let's get the O(1) lookup done first.
Eamon Walsh <ewalsh at tycho.nsa.gov>
National Security Agency
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