Subject: Re: [RFC][PATCH 5/7] UBC: kernel memory accounting (core)
From: Dave Hansen <haveblue@us.ibm.com>
To: Kirill Korotaev <dev@sw.ru>
Cc: Andrew Morton <akpm@osdl.org>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
       Alan Cox <alan@lxorguk.ukuu.org.uk>, Ingo Molnar <mingo@elte.hu>,
       Christoph Hellwig <hch@infradead.org>,
       Pavel Emelianov <xemul@openvz.org>, Andrey Savochkin <saw@sw.ru>,
       devel@openvz.org, Rik van Riel <riel@redhat.com>, hugh@veritas.com,
       ckrm-tech@lists.sourceforge.net, Andi Kleen <ak@suse.de>
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Date: Thu, 17 Aug 2006 07:36:19 -0700
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On Thu, 2006-08-17 at 17:31 +0400, Kirill Korotaev wrote:
> > How many things actually use this?  Can we have the slab ubcs
> without
> > the struct page pointer?
> slab doesn't use this pointer on the page.
> It is used for pages allocated by buddy
> alocator implicitly (e.g. LDT pages, page tables, ...). 

Hmmm.  There aren't _that_ many of those cases, right?  Are there any
that absolutely need raw access to the buddy allocator?  I'm pretty sure
that pagetables can be moved over to a slab, as long as we bump up the
alignment.

It does seem a wee bit silly to have the pointer in _all_ of the struct
pages, even the ones for which we will never do any accounting (and even
on kernels that never need it).  But, a hashing scheme sounds like a
fine idea.

-- Dave

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