linux-kernel - RE: [PATCH v3 1/1] kernel/sysctl.c: Add /proc/sys/vm/shrink

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Message-id: <030e01d0c9bd$20e1df60$62a59e20$@samsung.com>
Date:	Wed, 29 Jul 2015 10:41:10 +0530
From:	PINTU KUMAR <pintu.k@...sung.com>
To:	'Mel Gorman' <mgorman@...e.de>
Cc:	akpm@...ux-foundation.org, corbet@....net, vbabka@...e.cz,
	gorcunov@...nvz.org, mhocko@...e.cz, emunson@...mai.com,
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Subject: RE: [PATCH v3 1/1] kernel/sysctl.c: Add /proc/sys/vm/shrink_memory
 feature

Sorry, for late reply.

> -----Original Message-----
> From: Mel Gorman [mailto:mgorman@...e.de]
> Sent: Wednesday, July 22, 2015 7:36 PM
> To: PINTU KUMAR
> Cc: akpm@...ux-foundation.org; corbet@....net; 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; cj@...ux.com;
> opensource.ganesh@...il.com; vinmenon@...eaurora.org; linux-
> doc@...r.kernel.org; linux-kernel@...r.kernel.org; linux-mm@...ck.org; linux-
> pm@...r.kernel.org; qiuxishi@...wei.com; Valdis.Kletnieks@...edu;
> cpgs@...sung.com; pintu_agarwal@...oo.com; vishnu.ps@...sung.com;
> rohit.kr@...sung.com; iqbal.ams@...sung.com; pintu.ping@...il.com;
> pintu.k@...look.com
> Subject: Re: [PATCH v3 1/1] kernel/sysctl.c: Add /proc/sys/vm/shrink_memory
> feature
> 
> On Wed, Jul 22, 2015 at 06:33:26PM +0530, PINTU KUMAR wrote:
> > Dear Mel, thank you very much for your comments and suggestions.
> > I will drop this one and look on further improving direct_reclaim and
> > compaction.
> > Just few more comments below before I close.
> >
> > Also, during this patch, I feel that the hibernation_mode part in
> > shrink_all_memory can be corrected.
> > So, can I separately submit the below patch?
> > That is instead of hard-coding the hibernation_mode, we can get
> > hibernation status using:
> > system_entering_hibernation()
> >
> > Please let me know your suggestion about this changes.
> >
> > -#ifdef CONFIG_HIBERNATION
> > +#if defined CONFIG_HIBERNATION || CONFIG_SHRINK_MEMORY
> 
I was talking about only the following case.
Instead of hard coding the hibernation_mode in shrink_all_memory, 
We can set it at runtime.

-               .hibernation_mode = 1,

+       if (system_entering_hibernation())
+               sc.hibernation_mode = 1;
+       else
+               sc.hibernation_mode = 0;

The PM owners should confirm if this is ok.
Once confirmed, I will submit the full patch set.

+> This appears to be a patch on top of "Add /proc/sys/vm/shrink_memory feature"
> so I do not see what would be separately submitted that would make sense.
> 
And we don't need to have /proc/sys/vm/shrink_memory patch for this.

However, if required, we can also expose shrink_all_memory() outside the
hibernation using the CONFIG_SHRINK_MEMORY.
Otherwise, we can neglect other changes.

> --
> Mel Gorman
> SUSE Labs

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