linux-kernel - Re: [PATCH v4 0/3] zram/zsmalloc promotion

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Date:	Mon, 19 Nov 2012 10:27:29 +0900
From:	Minchan Kim <minchan@...nel.org>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Greg KH <gregkh@...uxfoundation.org>, linux-kernel@...r.kernel.org,
	linux-mm@...ck.org, Dan Magenheimer <dan.magenheimer@...cle.com>,
	Nitin Gupta <ngupta@...are.org>,
	Seth Jennings <sjenning@...ux.vnet.ibm.com>,
	Konrad Rzeszutek Wilk <konrad@...nok.org>,
	Jens Axboe <axboe@...nel.dk>,
	Pekka Enberg <penberg@...helsinki.fi>,
	gaowanlong@...fujitsu.com
Subject: Re: [PATCH v4 0/3] zram/zsmalloc promotion

Andrew?

On Wed, Nov 07, 2012 at 07:38:04PM +0900, Minchan Kim wrote:
> Hi Andrew,
> 
> On Wed, Nov 7, 2012 at 8:32 AM, Andrew Morton <akpm@...ux-foundation.org>
> wrote:
> > On Fri, 2 Nov 2012 16:12:44 +0900
> > Minchan Kim <minchan@...nel.org> wrote:
> >
> >> This patchset promotes zram/zsmalloc from staging.
> >
> > The changelogs are distressingly short of *reasons* for doing this!
> >
> >> Both are very clean and zram have been used by many embedded product
> >> for a long time.
> >
> > Well that's interesting.
> >
> > Which embedded products? How are they using zram and what benefit are
> > they observing from it, in what scenarios?
> >
> 
> At least, major TV companys have used zram as swap since two years ago and
> recently our production team released android smart phone with zram which
> is used as swap, too.
> And there is trial to use zram as swap in ChromeOS project, too. (Although
> they report some problem recently, it was not a problem of zram).
> When you google zram, you can find various usecase in xda-developers.
> 
> With my experience, the benefit in real practice was to remove jitter of
> video application. It would be effect of efficient memory usage by
> compression but more issue is whether swap is there or not in the system.
> As you know, recent mobile platform have used JAVA so there are lots of
> anonymous pages. But embedded system normally doesn't use eMMC or SDCard as
> swap because there is wear-leveling issue and latency so we can't reclaim
> anymous pages. It sometime ends up making system very slow when it requires
> to get contiguous memory and even many file-backed pages are evicted. It's
> never what embedded people want it. Zram is one of best solution for that.
> 
> It's very hard to type with mobile phone. :(
> 
> -- 
> Kind regards,
> Minchan Kim

-- 
Kind regards,
Minchan Kim
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