Re: [PATCH 2/3] page allocator: Do not allow interrupts to useALLOC_HARDER

From: David Rientjes
Date: Tue Nov 03 2009 - 20:47:10 EST

On Tue, 3 Nov 2009, Christoph Lameter wrote:

> If you dont know what "realtime" is then we cannot really implement
> "realtime" behavior in the page allocator.

It's not intended to implement realtime behavior!

This is a convenience given to rt_task() to reduce latency when possible
by avoiding direct reclaim and allowing background reclaim to bring us
back over the low watermark.

That's been in the page allocator for over four years and is not intended
to implement realtime behavior. These tasks do not rely on memory
reserves being available.

Is it really hard to believe that tasks with such high priorities are
given an exemption in the page allocator so that we reclaim in the
background instead of directly?

I hope we can move this to another thread if people would like to remove
this exemption completely instead of talking about this trivial fix, which
I doubt there's any objection to.
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