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Date: Tue, 15 May 2007 15:02:40 -0700 (PDT)
From: Christoph Lameter <clameter@sgi.com>
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To: Peter Zijlstra <a.p.zijlstra@chello.nl>
cc: Matt Mackall <mpm@selenic.com>, linux-kernel@vger.kernel.org,
       linux-mm@kvack.org, Thomas Graf <tgraf@suug.ch>,
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       Andrew Morton <akpm@linux-foundation.org>,
       Daniel Phillips <phillips@google.com>,
       Pekka Enberg <penberg@cs.helsinki.fi>
Subject: Re: [PATCH 0/5] make slab gfp fair
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On Tue, 15 May 2007, Peter Zijlstra wrote:

> How about something like this; it seems to sustain a little stress.

Argh again mods to kmem_cache.

Could we do this with a new slab page flag? F.e. SlabEmergPool.


in alloc_slab() do

if (is_emergency_pool_page(page)) {
	SetSlabDebug(page);
	SetSlabEmerg(page);
}

So now you can intercept allocs to the SlabEmerg slab in __slab_alloc 

debug:

if (SlabEmergPool(page)) {
	if (mem_no_longer_critical()) {
		/* Avoid future trapping */
		ClearSlabDebug(page);
		ClearSlabEmergPool(page);
	} else
	if (process_not_allowed_this_memory()) {
		do_something_bad_to_the_caller();
	} else {
		/* Allocation permitted */
	}
}

....