idea: set a niceness value under which a process won't awaken suspended CPU

[Jon Nettleton]

Although the idea sounds good, the mechanism of using nice is very 2007
:-)  This should be accomplished by putting this type of process in a
specific cgroup.  We can then use the cgroup freezer to freeze all tasks in
that group, and thaw it when we see fit.

I used a similar mechanism to fix the problem where my wife would have all
sorts of flash things running in different tabs of her web browser, when I
was switched over to my user profile on the netbook.  I added some hooks
into policy kit to thaw the background users cgroup and unthaw the logged
in user.  Really I could have just limited the amount of processor
resources they had access to, but why waste the battery?

Other than that I think this could be a very good thing.  I also think this
would be a good way to control things that we only want to run when plugged
in.  No reason to run some of those cpu intensive cron jobs when running on
battery.

-Jon

On Mar 2, 2012 9:44 AM, "John Gilmore" <gnu at toad.com> wrote:
>
> Here's a power-saving idea that's been marinating since 2007 (in an
> obscure corner of my mail queue).  When I reviewed it today I didn't
> see anything too wrong with it.
>
>        John
>
> Message-Id: <200710240912.l9O9C1k2026420 at new.toad.com>
> To: gnu
> Subject: OLPC idea: set a niceness value under which a process won't
awaken suspended CPU
> Date: Wed, 24 Oct 2007 02:12:01 -0700
> From: John Gilmore <gnu at toad.com>
>
> An easy lever for CPU consumption management (power mgmt) would be to
> define a set of user processes that won't be scheduled in a
> power-suspended system.  They won't wake the CPU even if their timer
> goes off, their packet arrives, or their fairy godmother calls.  But
> if something else wakes the CPU, and it's going to stay running a bit
> while some higher priority process is waiting for flash or packets or
> something, these processes can run in the background.
>
> My idea is to tie this to "nice".  So if you "nice -20", it puts you into
> this range.  Say everything below -15, which lets you set a few priorities
> among the low priority background stuff.
>
> So if you nice things all the way down, they run when the CPU is powered,
> in the cracks when there's nothing else to do, but they don't cause the
CPU
> to wake up to service them if nothing else is going on.
>
> For example, code that polls and updates the battery status once a
> minute in HAL.  Or a system activity monitor that shows CPU state
> graphs or how many MHz we're running.  Or an RSS feed reader.  Or the
> thing that clears out Mozilla's cache.  Or the incremental backup
> daemon that copies the machine's state to the school server.  (If that
> ran with scavenged electricity, cool!  It can raise its priority once
> a day or so, to make sure that a backup gets done one way or another.)
>
> The GUI could have a way to throw a process into this state or out of it.
> E.g. push your mail reader there, polling every once in a while for email,
> opportunistically.
>
>        John
>
> ------- End of Forwarded Message
>
> _______________________________________________
> Devel mailing list
> Devel at lists.laptop.org
> http://lists.laptop.org/listinfo/devel
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.laptop.org/pipermail/devel/attachments/20120302/4e28b10a/attachment.html>