linux-kernel - Re: [PATCH v2 5/6] mm: Support address range reclaim

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Date:	Thu, 25 Apr 2013 09:50:50 +0900
From:	Minchan Kim <minchan@...nel.org>
To:	Namhyung Kim <namhyung@...nel.org>
Cc:	Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	Michael Kerrisk <mtk.manpages@...il.com>,
	Rik van Riel <riel@...hat.com>,
	Dave Hansen <dave.hansen@...el.com>
Subject: Re: [PATCH v2 5/6] mm: Support address range reclaim

Hey Namhyung,

On Wed, Apr 24, 2013 at 08:01:48PM +0900, Namhyung Kim wrote:
> Hi Minchan,
> 
> On Wed, 24 Apr 2013 10:41:03 +0900, Minchan Kim wrote:
> > This patch adds address range reclaim of a process.
> > The requirement is following as,
> >
> > Like webkit1, it uses a address space for handling multi tabs.
> > IOW, it uses *one* process model so all tabs shares address space
> > of the process. In such scenario, per-process reclaim is rather
> > coarse-grained so this patch supports more fine-grained reclaim
> > for being able to reclaim target address range of the process.
> > For reclaim target range, you should use following format.
> >
> > 	echo [addr] [size-byte] > /proc/pid/reclaim
> >
> > addr should be page-aligned.
> >
> > So now reclaim konb's interface is following as.
> >
> > echo file > /proc/pid/reclaim
> > 	reclaim file-backed pages only
> >
> > echo anon > /proc/pid/reclaim
> > 	reclaim anonymous pages only
> >
> > echo all > /proc/pid/reclaim
> > 	reclaim all pages
> >
> > echo $((1<<20)) 8192 > /proc/pid/reclaim
> > 	reclaim pages in (0x100000 - 0x102000)
> >
> > Signed-off-by: Minchan Kim <minchan@...nel.org>
> > ---
> >  fs/proc/task_mmu.c | 88 ++++++++++++++++++++++++++++++++++++++++++++----------
> >  mm/internal.h      |  3 ++
> >  2 files changed, 76 insertions(+), 15 deletions(-)
> >
> > diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
> > index 79b674e..dff9756 100644
> > --- a/fs/proc/task_mmu.c
> > +++ b/fs/proc/task_mmu.c
> > @@ -12,6 +12,7 @@
> >  #include <linux/swap.h>
> >  #include <linux/swapops.h>
> >  #include <linux/mm_inline.h>
> > +#include <linux/ctype.h>
> >  
> >  #include <asm/elf.h>
> >  #include <asm/uaccess.h>
> > @@ -1239,11 +1240,14 @@ static ssize_t reclaim_write(struct file *file, const char __user *buf,
> >  				size_t count, loff_t *ppos)
> >  {
> >  	struct task_struct *task;
> > -	char buffer[PROC_NUMBUF];
> > +	char buffer[200];
> >  	struct mm_struct *mm;
> >  	struct vm_area_struct *vma;
> >  	enum reclaim_type type;
> >  	char *type_buf;
> > +	struct mm_walk reclaim_walk = {};
> > +	unsigned long start = 0;
> > +	unsigned long end = 0;
> >  
> >  	memset(buffer, 0, sizeof(buffer));
> >  	if (count > sizeof(buffer) - 1)
> > @@ -1259,42 +1263,96 @@ static ssize_t reclaim_write(struct file *file, const char __user *buf,
> >  		type = RECLAIM_ANON;
> >  	else if (!strcmp(type_buf, "all"))
> >  		type = RECLAIM_ALL;
> > +	else if (isdigit(*type_buf))
> > +		type = RECLAIM_RANGE;
> >  	else
> > -		return -EINVAL;
> > +		goto out_err;
> > +
> > +	if (type == RECLAIM_RANGE) {
> > +		int ret;
> > +		size_t len;
> > +		unsigned long len_in;
> > +		char *token;
> > +
> > +		token = strsep(&type_buf, " ");
> > +		if (!token)
> > +			goto out_err;
> > +		ret = kstrtoul(token, 10, &start);
> 
> Why not using
> 
> 		start = memparse(token, NULL);
> 
> to support something like:
> 
>   # echo 0x100000 8K > /proc/pid/reclaim
> 

Because I'm brain-damage. :(
Thanks for noticing useful function.

> 
> Thanks,
> Namhyung
> 
> --
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-- 
Kind regards,
Minchan Kim
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