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Subject: RE: [PATCH 2/5] vmevent: Convert from deferred timer to deferred
 work
Thread-Topic: [PATCH 2/5] vmevent: Convert from deferred timer to deferred
 work
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> -----Original Message-----
> From: ext Anton Vorontsov [mailto:anton.vorontsov@linaro.org]
> Sent: 08 June, 2012 11:41
...
> > Right. It but it has drawbacks as well e.g. ensure that daemon scheduled
> properly and propagate reaction decision outside ulmkd.
> 
> No, ulmkd itself propagates the decision (i.e. it kills processes).

That is a decision "select & kill" :)
Propagation of this decision required time. Not all processes could be killed. You may stuck in killing in some cases.
...
> In ulmkd I don't use timers at all, and by "watcher" I mean the some
> userspace daemon that receives lowmemory/pressure events (in our case it
> is ulmkd).

Thanks for info.

> If we start "polling" on /proc/vmstat via userland deferred timers, that would
> be a single timer, just like in vmevent case. So, I'm not sure what is the
> difference?..

Context switches, parsing, activity in userspace even memory situation is not changed. In kernel space you can use sliding timer (increasing interval) + shinker.
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