From: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
To: Andrea Arcangeli <aarcange@redhat.com>
Subject: Re: [PATCH 2/9] ksm: let shared pages be swappable
Cc: kosaki.motohiro@jp.fujitsu.com, Rik van Riel <riel@redhat.com>,
       KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
       Hugh Dickins <hugh.dickins@tiscali.co.uk>,
       Andrew Morton <akpm@linux-foundation.org>,
       Izik Eidus <ieidus@redhat.com>, Chris Wright <chrisw@redhat.com>,
       linux-kernel@vger.kernel.org, linux-mm@kvack.org
In-Reply-To: <20091203134610.586E.A69D9226@jp.fujitsu.com>
References: <20091202125501.GD28697@random.random> <20091203134610.586E.A69D9226@jp.fujitsu.com>
Message-Id: <20091204135938.5886.A69D9226@jp.fujitsu.com>
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Date: Fri,  4 Dec 2009 14:06:07 +0900 (JST)
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> Umm?? Personally I don't like knob. If you have problematic workload,
> please tell it us. I will try to make reproduce environment on my box.
> If current code doesn't works on KVM or something-else, I really want
> to fix it.
> 
> I think Larry's trylock idea and your 64 young bit idea can be combinate.
> I only oppose the page move to inactive list without clear young bit. IOW,
> if VM pressure is very low and the page have lots young bit, the page should
> go back active list although trylock(ptelock) isn't contended.
> 
> But unfortunatelly I don't have problem workload as you mentioned. Anyway
> we need evaluate way to your idea. We obviouslly more info.

[Off topic start]

Windows kernel have zero page thread and it clear the pages in free list
periodically. because many windows subsystem prerefer zero filled page.
hen, if we use windows guest, zero filled page have plenty mapcount rather
than other typical sharing pages, I guess.

So, can we mark as unevictable to zero filled ksm page? 


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