Re: [PATCH] VM fix for 2.4.0-test9 & OOM handler

[David Ford <david@kalifornia.com>]

Andreas Dilger wrote:

> Albert D. Cahalan wrote:
> > X, and any other big friendly processes, could participate in
> > memory balancing operations. X could be made to clean out a
>
> Gerrit Huizenga wrote:
> > Anyway, there is/was an API in PTX to say (either from in-kernel or through
> > some user machinations) "I Am a System Process".  Turns on a bit in the
>
> On AIX there is a signal called SIGDANGER, which is basically what you
> are looking for.  By default it is ignored, but for processes that care
> (e.g. init, X, whatever) they can register a SIGDANGER handler.  At an
> "urgent" (as oposed to "critical") OOM situation, all processes get a
> SIGDANGER sent to them.  Most will ignore it, but ones with handlers
> can free caches, try to do a clean shutdown, whatever.  Any process with
> a SIGDANGER handler get a reduction of "badness" (as the OOM killer calls
> it) when looking for processes to kill.
>
> Having a SIGDANGER handler is good for 2 reasons:
> 1) Lets processes know when memory is short so they can free needless cache.
> 2) Mark process with a SIGDANGER handler as "more important" than those
>    without.  Most people won't care about this, but init, and X, and
>    long-running simulations might.

Is there any reason why we can't do something like this for 2.5?

-d

--
      "There is a natural aristocracy among men. The grounds of this are
      virtue and talents", Thomas Jefferson [1742-1826], 3rd US President



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