linux-kernel - Re: [PATCH v1 0/3] per-process reclaim

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Date:	Wed, 15 Jun 2016 09:43:34 +0900
From:	Minchan Kim <minchan@...nel.org>
To:	Chen Feng <puck.chen@...ilicon.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	Rik van Riel <riel@...hat.com>,
	Redmond <u93410091@...il.com>,
	"ZhaoJunmin Zhao(Junmin)" <zhaojunmin@...wei.com>,
	Vinayak Menon <vinmenon@...eaurora.org>,
	Juneho Choi <juno.choi@....com>,
	Sangwoo Park <sangwoo2.park@....com>,
	Chan Gyun Jeong <chan.jeong@....com>
Subject: Re: [PATCH v1 0/3] per-process reclaim

Hi Chen,

On Mon, Jun 13, 2016 at 07:50:00PM +0800, Chen Feng wrote:
> Hi Minchan,
> 
> On 2016/6/13 15:50, Minchan Kim wrote:
> > Hi all,
> > 
> > http://thread.gmane.org/gmane.linux.kernel/1480728
> > 
> > I sent per-process reclaim patchset three years ago. Then, last
> > feedback from akpm was that he want to know real usecase scenario.
> > 
> > Since then, I got question from several embedded people of various
> > company "why it's not merged into mainline" and heard they have used
> > the feature as in-house patch and recenlty, I noticed android from
> > Qualcomm started to use it.
> > 
> > Of course, our product have used it and released it in real procuct.
> > 
> > Quote from Sangwoo Park <angwoo2.park@....com>
> > Thanks for the data, Sangwoo!
> > "
> > - Test scenaro
> >   - platform: android
> >   - target: MSM8952, 2G DDR, 16G eMMC
> >   - scenario
> >     retry app launch and Back Home with 16 apps and 16 turns
> >     (total app launch count is 256)
> >   - result:
> > 			  resume count   |  cold launching count
> > -----------------------------------------------------------------
> >  vanilla           |           85        |          171
> >  perproc reclaim   |           184       |           72
> > "
> > 
> > Higher resume count is better because cold launching needs loading
> > lots of resource data which takes above 15 ~ 20 seconds for some
> > games while successful resume just takes 1~5 second.
> > 
> > As perproc reclaim way with new management policy, we could reduce
> > cold launching a lot(i.e., 171-72) so that it reduces app startup
> > a lot.
> > 
> > Another useful function from this feature is to make swapout easily
> > which is useful for testing swapout stress and workloads.
> > 
> Thanks Minchan.
> 
> Yes, this is useful interface when there are memory pressure and let the userspace(Android)
> to pick process for reclaim. We also take there series into our platform.
> 
> But I have a question on the reduce app startup time. Can you also share your
> theory(management policy) on how can the app reduce it's startup time?

What I meant about start-up time is as follows,

If a app is killed, it should launch from start so if it was the game app,
it should load lots of resource file which takes a long time.
However, if the game was not killed, we can enjoy the game without cold
start so it is very fast startup.

Sorry for confusing.