From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oa0-f77.google.com (mail-oa0-f77.google.com [209.85.219.77]) by kanga.kvack.org (Postfix) with ESMTP id C5B8E6B0031 for ; Fri, 13 Dec 2013 09:56:35 -0500 (EST) Received: by mail-oa0-f77.google.com with SMTP id o6so35172oag.8 for ; Fri, 13 Dec 2013 06:56:35 -0800 (PST) Received: from blackbird.sr71.net ([2001:19d0:2:6:209:6bff:fe9a:902]) by mx.google.com with ESMTP id j69si22614650yhb.296.2013.12.12.11.29.35 for ; Thu, 12 Dec 2013 11:29:36 -0800 (PST) Message-ID: <52AA0E5D.30903@sr71.net> Date: Thu, 12 Dec 2013 11:28:29 -0800 From: Dave Hansen MIME-Version: 1.0 Subject: Re: [PATCH] [RFC] mm: slab: separate slab_page from 'struct page' References: <20131210204641.3CB515AE@viggo.jf.intel.com> <00000142de5634af-f92870a7-efe2-45cd-b50d-a6fbdf3b353c-000000@email.amazonses.com> <52A78B55.8050500@sr71.net> <00000142de866123-cf1406b5-b7a3-4688-b46f-80e338a622a1-000000@email.amazonses.com> <52A793D0.4020306@sr71.net> <00000142e7e23135-20f346b1-a880-47b0-946c-122323669ec1-000000@email.amazonses.com> In-Reply-To: <00000142e7e23135-20f346b1-a880-47b0-946c-122323669ec1-000000@email.amazonses.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Christoph Lameter Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, kirill.shutemov@linux.intel.com, Andi Kleen On 12/12/2013 09:37 AM, Christoph Lameter wrote: > On Tue, 10 Dec 2013, Dave Hansen wrote: >> See? *EVERYTHING* is overridden by at least one of the sl?b allocators >> except ->flags. In other words, there *ARE* no relationships when it >> comes to the sl?bs, except for page->flags. > > Slab objects can be used for I/O and then the page fields become > important. OK, which fields? How are they important? Looking at 'struct page', I don't see any fields other than ->flags that the slab allocators leave alone. I do see some refcounting (page->_count) done on request_queue->dma_drain_buffer which is kmalloc()'d. Although, I'm a bit skeptical that this is correct or has been audited because the slabs do seem to write over this storage. Anything needing to do per-page could probably be converted over to a raw alloc_pages() anyway because it couldn't possibly be doing sub-page-size allocations. What other cases were you thinking of? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org