dpkg --list | grep gamemode

Check if both are really installed, typically happens when the game you're trying to run is a 32-bit application, but the preloaded gamemode library is for 64-bit.

Thanks for the response. I had already installed the i386 libs, which resolved the wrong ELF class error ... but here's the dpkg --list, and the gamemoded test showing everything passes ...
-----------------------------------------------------------
$ dpkg --list | grep gamemode
ii gamemode 1.6.1-1build2 amd64 Optimise Linux system performance on demand
ii gamemode-daemon 1.6.1-1build2 amd64 Optimise Linux system performance on demand (daemon)
ii libgamemode0:amd64 1.6.1-1build2 amd64 Optimise Linux system performance on demand (host library)
ii libgamemode0:i386 1.6.1-1build2 i386 Optimise Linux system performance on demand (host library)
ii libgamemodeauto0:amd64 1.6.1-1build2 amd64 Optimise Linux system performance on demand (client library)
ii libgamemodeauto0:i386 1.6.1-1build2 i386 Optimise Linux system performance on demand (client library)
-----------------------------------------------------------
$ gamemoded -t
: Loading config
Loading config file [/usr/share/gamemode/gamemode.ini]
: Running tests

:: Basic client tests
:: Passed

:: Dual client tests
gamemode request succeeded and is active
Quitting by request...
:: Passed

:: Gamemoderun and reaper thread tests
...Waiting for child to quit...
...Waiting for reaper thread (reaper_frequency set to 5 seconds)...
:: Passed

:: Supervisor tests
:: Passed

:: Feature tests
::: Verifying CPU governor setting
::: Passed
::: Verifying Scripts
::: Passed (no scripts configured to run)
::: Verifying GPU Optimisations
::: Passed (gpu optimisations not configured to run)
::: Verifying renice
::: Passed (no renice configured)
::: Verifying ioprio
::: Passed
:: Passed

: All Tests Passed!
-----------------------------------------------------------
Not sure if this error is benign, or something I need to resolve ... though when I see ERROR I am compelled to defeat it.

did you download and install the 32-bit gamemode library?

Publicado originalmente por Long:

did you download and install the 32-bit gamemode library?

Yes, as stated in both of my posts above the i386 libs for gamemode are installed.

Did you verify, does it work in-game? As test seems to pass and if it works, i would just ignore it atm:) The error seems to refer that dynbamic linker is not found or something.

PS! IF any game crashes, first thing is to try running without gamemode.

Publicado originalmente por Vulcanus:

Did you verify, does it work in-game? As test seems to pass and if it works, i would just ignore it atm:) The error seems to refer that dynbamic linker is not found or something.

PS! IF any game crashes, first thing is to try running without gamemode.

not had any problems with games crashing, I checked gamemode while a game is active (alt-tabbed) and it's working:
so I'm guessing it's a benign error that simply means it can't be preloaded, but it will run on demand ... at least that's my current theory.