linux-kernel - Re: [PATCH 4/7] Allow sysfs memory directories to be split

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Message-Id: <20100714093550.40036034.kamezawa.hiroyu@jp.fujitsu.com>
Date:	Wed, 14 Jul 2010 09:35:50 +0900
From:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To:	Nathan Fontenot <nfont@...tin.ibm.com>
Cc:	linux-kernel@...r.kernel.org, linuxppc-dev@...abs.org,
	Dave Hansen <dave@...ux.vnet.ibm.com>
Subject: Re: [PATCH 4/7] Allow sysfs memory directories to be split

On Tue, 13 Jul 2010 10:51:58 -0500
Nathan Fontenot <nfont@...tin.ibm.com> wrote:

> > 
> > And for what purpose this interface is ? Does this split memory block into 2 pieces
> > of the same size ?? sounds __very__ strange interface to me.
> 
> Yes, this splits the memory_block into two blocks of the same size.  This was
> suggested as something we may want to do.  From ppc perspective I am not sure we
> would use this.
> 
> The split functionality is not required.  The main goal of the patch set is to
> reduce the number of memory sysfs directories created.  From a ppc perspective
> the split functionality is not really needed.
> 

Okay, this is an offer from me.

  1. I think you can add an boot option as "don't create memory sysfs".
     please do.

  2. I'd like to write a configfs module for handling memory hotplug even when
     sysfs directroy is not created.
     Because configfs support rmdir/mkdir, the user (ppc's daemon?) has to do
     
     When offlining section X.
     # insmod configfs_memory.ko
     # mount -t configfs none /configfs
     # mkdir /configfs/memoryX
     # echo offline > /configfs/memoryX/state
     # rmdir /configfs/memoryX

  And making this operation as the default bahavior for all arch's memory hotplug may
  be better...

Dave, how do you think ? Because ppc guys uses "probe" interface already,
this can be handled... no ?

One problem is that I don't have enough knowledge about configfs..it seems complex.

Thanks,
-Kame
  

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