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Message-ID: <1503351645.6577.76.camel@redhat.com>
Subject: Re: [RFC PATCH 0/6] proactive kcompactd
From: Rik van Riel <riel@redhat.com>
Date: Mon, 21 Aug 2017 17:40:45 -0400
In-Reply-To: <20170821141014.GC1371@cmpxchg.org>
References: <20170727160701.9245-1-vbabka@suse.cz>
	 <alpine.DEB.2.10.1708091353500.1218@chino.kir.corp.google.com>
	 <20170821141014.GC1371@cmpxchg.org>
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To: Johannes Weiner <hannes@cmpxchg.org>, David Rientjes <rientjes@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>, linux-mm@kvack.org, Joonsoo Kim <iamjoonsoo.kim@lge.com>, Mel Gorman <mgorman@techsingularity.net>, Michal Hocko <mhocko@kernel.org>, Andrea Arcangeli <aarcange@redhat.com>

On Mon, 2017-08-21 at 10:10 -0400, Johannes Weiner wrote:
> 
> I've been toying around with the below patch. It adds a free page
> bitmap, allowing the free scanner to quickly skip over the vast areas
> of used memory. I don't have good data on skip-efficiency at higher
> uptimes and the resulting fragmentation yet. The overhead added to
> the
> page allocator is concerning, but I cannot think of a better way to
> make the search more efficient. What do you guys think?

Michael Tsirkin and I have been thinking about using a bitmap
to allow KVM guests to tell the host which pages are free (and
could be discarded by the host).

Having multiple users for the bitmap makes having one much more
compelling...

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