Re: [PATCH] memory hotplug disable boot option

[Greg KH]

On Wed, Jun 30, 2010 at 09:32:51AM +0900, KAMEZAWA Hiroyuki wrote:
> On Tue, 29 Jun 2010 11:04:15 -0700
> Greg KH <gregkh@xxxxxxx> wrote:
> 
> > On Tue, Jun 29, 2010 at 09:03:04AM -0700, Dave Hansen wrote:
> > > On Tue, 2010-06-29 at 11:56 +0900, KOSAKI Motohiro wrote:
> > > > > On Mon, 2010-06-28 at 08:44 -0700, Greg KH wrote:
> > > > > > > The directories being created are the standard directories, one for each of the memory
> > > > > > > sections present at boot.  I think the most used files in each of these directories
> > > > > > > is the state and removable file used to do memory hotplug.
> > > > > > 
> > > > > > And perhaps we shouldn't really be creating so many directories?  Why
> > > > > > not work with the memory hotplug developers to change their interface to
> > > > > > not abuse sysfs in such a manner? 
> > > > > 
> > > > > Heh, it wasn't abuse until we got this much memory.  But, I think this
> > > > > one is pretty much 100% my fault.
> > > > > 
> > > > > Nathan, I think the right fix here is probably to untie sysfs from the
> > > > > sections a bit.  We should be able to have sysfs dirs that represent
> > > > > more than one contiguous SECTION_SIZE area of memory.
> > > > 
> > > > Why do we need abi breakage? Yourself talked about we guess ppc don't
> > > > actually need 16MB section. I think IBM folks have to confirm it.
> > > > If our guessing is correct, the firmware fixing is only necessary.
> > > 
> > > >From the mouth of the kernel dumbass who coded this up: it's not the
> > > firmware's fault.  We shouldn't punt this to them, and the proper fix
> > > _isn't_ in the firmware, plus they may have other more fundamental
> > > reasons to keep the LMB sizes what they are.
> > 
> > I agree, this should be fixed in the api to userspace, having this many
> > sysfs directories and/or files is just looney.
> > 
> > thanks,
> > 
> 
> Hmm, adding 
>  CONFIG_NEW_MEMORY_SYSFS_LAYOUT or

It will not be "NEW" in a year :)

>  memory_sysfs_layout=small boot option

Yes, that sounds good.

> and adding a scalable interface for large scale machines ?
> I'd like to consider something..

Dynamically changing the layout on big memory boxes makes sense to me,
how about you?

thanks,

greg k-h
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