Date: Wed, 29 Jul 2015 12:55:54 +0200
From: Daniel Vetter <daniel@ffwll.ch>
To: Mel Gorman <mgorman@techsingularity.net>
Cc: Gioh Kim <gioh.kim@lge.com>, jlayton@poochiereds.net, bfields@fieldses.org,
        vbabka@suse.cz, iamjoonsoo.kim@lge.com, viro@zeniv.linux.org.uk,
        mst@redhat.com, koct9i@gmail.com, minchan@kernel.org,
        aquini@redhat.com, linux-fsdevel@vger.kernel.org,
        virtualization@lists.linux-foundation.org,
        linux-kernel@vger.kernel.org, linux-api@vger.kernel.org,
        linux-mm@kvack.org, dri-devel@lists.freedesktop.org,
        akpm@linux-foundation.org, Gioh Kim <gurugio@hanmail.net>
Subject: Re: [PATCH 0/4] enable migration of driver pages
Message-ID: <20150729105554.GU16722@phenom.ffwll.local>
Mail-Followup-To: Mel Gorman <mgorman@techsingularity.net>,
	Gioh Kim <gioh.kim@lge.com>, jlayton@poochiereds.net,
	bfields@fieldses.org, vbabka@suse.cz, iamjoonsoo.kim@lge.com,
	viro@zeniv.linux.org.uk, mst@redhat.com, koct9i@gmail.com,
	minchan@kernel.org, aquini@redhat.com,
	linux-fsdevel@vger.kernel.org,
	virtualization@lists.linux-foundation.org,
	linux-kernel@vger.kernel.org, linux-api@vger.kernel.org,
	linux-mm@kvack.org, dri-devel@lists.freedesktop.org,
	akpm@linux-foundation.org, Gioh Kim <gurugio@hanmail.net>
References: <1436776519-17337-1-git-send-email-gioh.kim@lge.com>
 <20150729104945.GA30872@techsingularity.net>
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On Wed, Jul 29, 2015 at 11:49:45AM +0100, Mel Gorman wrote:
> On Mon, Jul 13, 2015 at 05:35:15PM +0900, Gioh Kim wrote:
> > My ARM-based platform occured severe fragmentation problem after long-term
> > (several days) test. Sometimes even order-3 page allocation failed. It has
> > memory size 512MB ~ 1024MB. 30% ~ 40% memory is consumed for graphic processing
> > and 20~30 memory is reserved for zram.
> > 
> 
> The primary motivation of this series is to reduce fragmentation by allowing
> more kernel pages to be moved. Conceptually that is a worthwhile goal but
> there should be at least one major in-kernel user and while balloon
> pages were a good starting point, I think we really need to see what the
> zram changes look like at the same time.

I think gpu drivers really would be the perfect candidate for compacting
kernel page allocations. And this also seems the primary motivation for
this patch series, so I think that's really what we should use to judge
these patches.

Of course then there's the seemingly eternal chicken/egg problem of
upstream gpu drivers for SoCs :(
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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