From: PINTU KUMAR <pintu.k@samsung.com>
To: "'Xishi Qiu'" <qiuxishi@huawei.com>
Cc: corbet@lwn.net, akpm@linux-foundation.org, vbabka@suse.cz,
        gorcunov@openvz.org, mhocko@suse.cz, emunson@akamai.com,
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        minchan@kernel.org, tj@kernel.org, rientjes@google.com,
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References: <1435929607-3435-1-git-send-email-pintu.k@samsung.com>
 <559A56FD.6010701@huawei.com>
In-reply-to: <559A56FD.6010701@huawei.com>
Subject: RE: [PATCH 1/1] kernel/sysctl.c: Add /proc/sys/vm/shrink_memory feature
Date: Mon, 06 Jul 2015 19:33:36 +0530
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Hi,

> -----Original Message-----
> From: Xishi Qiu [mailto:qiuxishi@huawei.com]
> Sent: Monday, July 06, 2015 3:53 PM
> To: Pintu Kumar
> Cc: corbet@lwn.net; akpm@linux-foundation.org; vbabka@suse.cz;
> gorcunov@openvz.org; mhocko@suse.cz; emunson@akamai.com;
> kirill.shutemov@linux.intel.com; standby24x7@gmail.com;
> hannes@cmpxchg.org; vdavydov@parallels.com; hughd@google.com;
> minchan@kernel.org; tj@kernel.org; rientjes@google.com;
> xypron.glpk@gmx.de; dzickus@redhat.com; prarit@redhat.com;
> ebiederm@xmission.com; rostedt@goodmis.org; uobergfe@redhat.com;
> paulmck@linux.vnet.ibm.com; iamjoonsoo.kim@lge.com; ddstreet@ieee.org;
> sasha.levin@oracle.com; koct9i@gmail.com; mgorman@suse.de; cj@linux.com;
> opensource.ganesh@gmail.com; vinmenon@codeaurora.org; linux-
> doc@vger.kernel.org; linux-kernel@vger.kernel.org; linux-mm@kvack.org; linux-
> pm@vger.kernel.org; cpgs@samsung.com; pintu_agarwal@yahoo.com;
> vishnu.ps@samsung.com; rohit.kr@samsung.com; iqbal.ams@samsung.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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