linux-kernel - RE: [PATCH 1/1] kernel/sysctl.c: Add /proc/sys/vm/shrink

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Message-id: <0ffe01d0b7f4$dd2706d0$97751470$@samsung.com>
Date:	Mon, 06 Jul 2015 19:33:36 +0530
From:	PINTU KUMAR <pintu.k@...sung.com>
To:	'Xishi Qiu' <qiuxishi@...wei.com>
Cc:	corbet@....net, akpm@...ux-foundation.org, vbabka@...e.cz,
	gorcunov@...nvz.org, mhocko@...e.cz, emunson@...mai.com,
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	rohit.kr@...sung.com, iqbal.ams@...sung.com
Subject: RE: [PATCH 1/1] kernel/sysctl.c: Add /proc/sys/vm/shrink_memory feature

Hi,

> -----Original Message-----
> From: Xishi Qiu [mailto:qiuxishi@...wei.com]
> Sent: Monday, July 06, 2015 3:53 PM
> To: Pintu Kumar
> Cc: corbet@....net; akpm@...ux-foundation.org; vbabka@...e.cz;
> gorcunov@...nvz.org; mhocko@...e.cz; emunson@...mai.com;
> kirill.shutemov@...ux.intel.com; standby24x7@...il.com;
> hannes@...xchg.org; vdavydov@...allels.com; hughd@...gle.com;
> minchan@...nel.org; tj@...nel.org; rientjes@...gle.com;
> xypron.glpk@....de; dzickus@...hat.com; prarit@...hat.com;
> ebiederm@...ssion.com; rostedt@...dmis.org; uobergfe@...hat.com;
> paulmck@...ux.vnet.ibm.com; iamjoonsoo.kim@....com; ddstreet@...e.org;
> sasha.levin@...cle.com; koct9i@...il.com; mgorman@...e.de; cj@...ux.com;
> opensource.ganesh@...il.com; vinmenon@...eaurora.org; linux-
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> pm@...r.kernel.org; cpgs@...sung.com; pintu_agarwal@...oo.com;
> vishnu.ps@...sung.com; rohit.kr@...sung.com; iqbal.ams@...sung.com
> Subject: Re: [PATCH 1/1] kernel/sysctl.c: Add /proc/sys/vm/shrink_memory
> feature
> 
> On 2015/7/3 21:20, Pintu Kumar wrote:
> 
> > This patch provides 2 things:
> > 1. Add new control called shrink_memory in /proc/sys/vm/.
> > This control can be used to aggressively reclaim memory system-wide in
> > one shot from the user space. A value of 1 will instruct the kernel to
> > reclaim as much as totalram_pages in the system.
> > Example: echo 1 > /proc/sys/vm/shrink_memory
> >
> > 2. Enable shrink_all_memory API in kernel with new
> CONFIG_SHRINK_MEMORY.
> > Currently, shrink_all_memory function is used only during hibernation.
> > With the new config we can make use of this API for non-hibernation
> > case also without disturbing the hibernation case.
> >
> > The detailed paper was presented in Embedded Linux Conference,
> > Mar-2015 http://events.linuxfoundation.org/sites/events/files/slides/
> > %5BELC-2015%5D-System-wide-Memory-Defragmenter.pdf
> >
> > Scenarios were this can be used and helpful are:
> > 1) Can be invoked just after system boot-up is finished.
> > 2) Can be invoked just before entering entire system suspend.
> > 3) Can be invoked from kernel when order-4 pages starts failing.
> > 4) Can be helpful to completely avoid or delay the kerenl OOM condition.
> > 5) Can be developed as a system-tool to quickly defragment entire system
> >    from user space, without the need to kill any application.
> >
> 
> Hi Pintu,
> 
> How about increase min_free_kbytes and Android lowmemorykiller's level?
> 
Thanks for the review.
Actually in Tizen, we don't use Android LMK and we wanted to delay the LMK with
aggressive direct_reclaim offline.
And increasing min_free value also may not help much.
Currently, in our case free memory never falls below 10MB, with 512MB RAM
configuration.


> Thanks,
> Xishi Qiu

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