X Server: abused or buggy?

[Lubos Lunak]

On Tuesday 09 of December 2008, Óscar Fuentes wrote:
> After observing how X used 1.3 GB of RAM, some investigation revealed
> that certain application (Okular, a document viewer,
> http://okular.kde.org) was causing this memory consumption. It is
> creating lots of pixmaps as a way for caching document pages. Opening a
> pdf file an scrolling through its pages makes X memory usage grow in the
> hundreds of MB. After Okular is closed, usually X returns the memory to
> the OS. But not always, sometimes retains some dozens of MB.
>
> Is this considered a bug on the X server, or is it being abused by the
> application?

 Neither. Pixmaps created by applications are normally stored in the X server, 
and in this specific case this optimization is a feature and can be 
configured in Okular's configuration.

 Moreover I'd assume that you interpret memory usage numbers incorrectly 
(simply because almost everyone does). I suggest to use the 'xrestop' tool to 
check how X resources are used by applications and find some good explanation 
of numbers reported by 'top', 'free' or whatever tool you used. If you can 
still confirm an unreasonable memory usage afterwards, you can report a bug 
at http://bugs.kde.org .

-- 
Lubos Lunak
KDE developer
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