Re: The future of session management in GNOME

Tommi Komulainen wrote:
On 9/13/06, Brian Nitz <Brian Nitz sun com> wrote:
Why do we ever log out?
    4) Free up resources.   ???

Reason 4 is especially interesting for multiuser systems, especially
thin clients.  It might be interesting for embedded uses of GNOME
(laptop/child, maemo...) to reduce resources when user isn't looking.

For single user embedded case I can't suddenly think of anything
logging out would provide that idle/screensaver mode and offline mode
wouldn't. When the user isn't watching you should've already stopped
all timers and screen updates. Except for possible music playing and
network transfers, when the screen is blanked nothing should be
I agree, what I'm proposing is a unified method of using "I'm not present" information to stop timers and screen updates instead of logging out.

For embedded you have control over timers and screen updates, but my guess is that maemo has their own solution and OLPC has another one and multiuser yet another. For desktop and laptop PCs you can invoke the kernel's power management to save the state of the entire machine (rather than the session), but this doesn't work for multiuser.
Also doing more work (saving state, shutting down applications) just
to do more work later (restarting the apps, restoring state) might not
be the brightest idea unless you know the extra memory would be better
spent elsewhere (but where? nothing should be happening when the user
isn't looking.)
Yes. That's why I was considering a way of avoiding logout and yet avoid consuming resources when the user isn't present. But now that I look at it, when the screen is blank and I have terminal, evolution and a few other apps running, only at-spi-registryd and mixer_applet2 appear hot enough to be worth bothering about. Memory usage while idle is a more significant issue. In multiuser its obvious where the extra memory would be used. In embedded its more a matter of reducing power consumption by avoiding cache misses to flash or disk. But if the kernel is doing it's job, memory from idle user processes should be paged out, so I think we're better off attacking that problem by reducing general bloat rather than introducing page/swap complexity into the session manager.

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