linux-kernel - Re: [PATCH] memory hotplug disable boot option

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Message-ID: <20100628141615.GA7608@basil.fritz.box>
Date:	Mon, 28 Jun 2010 16:16:15 +0200
From:	Andi Kleen <andi@...stfloor.org>
To:	"Eric W. Biederman" <ebiederm@...ssion.com>
Cc:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Nathan Fontenot <nfont@...tin.ibm.com>,
	Andi Kleen <andi@...stfloor.org>, linux-kernel@...r.kernel.org,
	Greg Kroah-Hartman <gregkh@...e.de>
Subject: Re: [PATCH] memory hotplug disable boot option

> I have a prototype patch sitting around somewhere.  I think ultimately
> it makes sense to do something like extN's htree directory structure
> in sysfs.  I wanted to get the tagged sysfs support in before I worked
> on scalability because that slightly changes the requirements.
> 
> Improving the scalability here is certainly worth doing, but I am slightly
> concerned there is something else algorithmically wrong if this is still
> going to take 33 minutes to boot with 2TB.

I'm don't think thousands of entries in sysfs is really a good idea. Even if you fix
the the insert algorithm issues a simple ls will still be very slow and there
will be likely other issues too. And nobody can claim that's a good interface.

This really needs a better a interface.
e.g. add some wildcard entry as it was earlier proposed.
and only generate the wildcard when some threshold is exceeded.

-Andi
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