linux-kernel - Re: [PATCH 6/6] add documentation on proc.txt

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Message-ID: <20130423012638.GB2603@blaptop>
Date:	Tue, 23 Apr 2013 10:26:38 +0900
From:	Minchan Kim <minchan@...nel.org>
To:	Rob Landley <rob@...dley.net>
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>
Subject: Re: [PATCH 6/6] add documentation on proc.txt

Hello Rob,

On Mon, Apr 22, 2013 at 10:48:39AM -0500, Rob Landley wrote:
> On 04/22/2013 03:45:06 AM, Minchan Kim wrote:
> >This patch adds documentation about new reclaim field in proc.txt
> >
> >Cc: Rob Landley <rob@...dley.net>
> >Signed-off-by: Minchan Kim <minchan@...nel.org>
> >---
> > Documentation/filesystems/proc.txt | 24 ++++++++++++++++++++++++
> > 1 file changed, 24 insertions(+)
> >
> >diff --git a/Documentation/filesystems/proc.txt
> >b/Documentation/filesystems/proc.txt
> >index 488c094..c1f5ee4 100644
> >--- a/Documentation/filesystems/proc.txt
> >+++ b/Documentation/filesystems/proc.txt
> >@@ -136,6 +136,7 @@ Table 1-1: Process specific entries in /proc
> >  maps		Memory maps to executables and library files	(2.4)
> >  mem		Memory held by this process
> >  root		Link to the root directory of this process
> >+ reclaim	Reclaim pages in this process
> >  stat		Process status
> >  statm		Process memory status information
> >  status		Process status in human readable form
> >@@ -489,6 +490,29 @@ To clear the soft-dirty bit
> >
> > Any other value written to /proc/PID/clear_refs will have no effect.
> >
> >+The /proc/PID/reclaim is used to reclaim pages in this process.
> 
> Trivial nitpick: Either start with "The file" or just /proc/PID/reclaim

I prefer "The file".

> 
> >+To reclaim file-backed pages,
> >+    > echo 1 > /proc/PID/reclaim
> >+
> >+To reclaim anonymous pages,
> >+    > echo 2 > /proc/PID/reclaim
> >+
> >+To reclaim both pages,
> >+    > echo 3 > /proc/PID/reclaim
> >+
> >+Also, you can specify address range of process so part of address
> >space
> >+will be reclaimed. The format is following as
> >+    > echo 4 addr size > /proc/PID/reclaim
> 
> Size is in bytes or pages? (I'm guessing bytes. It must be a
> multiple of pages?)

Hmm, current implementation doesn't force it but it sounds good.
I will do it in next spin. addr should be page-aligned but not necessary
to be for size.


> 
> So the following examples are telling it to reclaim a specific page?

Right.

> 
> >+To reclaim file-backed pages in address range,
> >+    > echo 4 $((1<<20) 4096 > /proc/PID/reclaim
> >+
> >+To reclaim anonymous pages in address range,
> >+    > echo 5 $((1<<20) 4096 > /proc/PID/reclaim
> >+
> >+To reclaim both pages in address range,
> >+    > echo 6 $((1<<20) 4096 > /proc/PID/reclaim
> >+
> > The /proc/pid/pagemap gives the PFN, which can be used to find
> >the pageflags
> > using /proc/kpageflags and number of times a page is mapped using
> > /proc/kpagecount. For detailed explanation, see
> >Documentation/vm/pagemap.txt.
> 
> Otherwise, if the series goes in I'm fine with this going in with it.
> 
> Acked-by: Rob Landley <rob@...dley.net>

Thanks for the review!

> 
> Rob
> --
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-- 
Kind regards,
Minchan Kim
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