linux-kernel - Re: [RFC][-mm][PATCH 3/6] oom-killer: count lowmem rss

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Date:	Tue, 3 Nov 2009 08:11:29 +0900 (JST)
From:	"KAMEZAWA Hiroyuki" <kamezawa.hiroyu@...fujitsu.com>
To:	"Christoph Lameter" <cl@...ux-foundation.org>
Cc:	"KAMEZAWA Hiroyuki" <kamezawa.hiroyu@...fujitsu.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	"kosaki.motohiro@...fujitsu.com" <kosaki.motohiro@...fujitsu.com>,
	aarcange@...hat.com, akpm@...ux-foundation.org,
	minchan.kim@...il.com, rientjes@...gle.com, vedran.furac@...il.com,
	"hugh.dickins@...cali.co.uk" <hugh.dickins@...cali.co.uk>
Subject: Re: [RFC][-mm][PATCH 3/6] oom-killer: count lowmem rss

Christoph Lameter wrote:
>
> I dont think this patch will work in !NUMA but its useful there too. Can
> you make this work in general?
>
for NUMA
==
+static inline int is_lowmem_page(struct page *page)
+{
+	if (unlikely(page_zonenum(page) < policy_zone))
+		return 1;
+	return 0;
+}
==

is used. Doesn't this work well ?
This check means
It enough memory:
   On my ia64 box ZONE_DMA(<4G), x86-64 box(GFP_DMA32) is caught
If small memory (typically < 4G)
   ia64 box no lowmem, x86-64 box GPF_DMA is caught
If all zones are policy zone (ppc)
   no lowmem zone.

Because "amount of memory" changes the situation "which is lowmem?",
I used policy zone. If this usage is not appropriate, I'll add some new.

BTW, is it better to export this value from somewhere ?

Thanks,
-Kame


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