From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from westrelay02.boulder.ibm.com (westrelay02.boulder.ibm.com [9.17.195.11]) by e36.co.us.ibm.com (8.12.11/8.12.11) with ESMTP id k0QNOYkV024909 for ; Thu, 26 Jan 2006 18:24:34 -0500 Received: from d03av02.boulder.ibm.com (d03av02.boulder.ibm.com [9.17.195.168]) by westrelay02.boulder.ibm.com (8.12.10/NCO/VERS6.8) with ESMTP id k0QNMjeQ235014 for ; Thu, 26 Jan 2006 16:22:45 -0700 Received: from d03av02.boulder.ibm.com (loopback [127.0.0.1]) by d03av02.boulder.ibm.com (8.12.11/8.13.3) with ESMTP id k0QNOXPp011027 for ; Thu, 26 Jan 2006 16:24:33 -0700 Message-ID: <43D95A2E.4020002@us.ibm.com> Date: Thu, 26 Jan 2006 15:24:30 -0800 From: Matthew Dobson MIME-Version: 1.0 Subject: Re: [patch 3/9] mempool - Make mempools NUMA aware References: <20060125161321.647368000@localhost.localdomain> <1138233093.27293.1.camel@localhost.localdomain> <43D953C4.5020205@us.ibm.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: Christoph Lameter Cc: linux-kernel@vger.kernel.org, sri@us.ibm.com, andrea@suse.de, pavel@suse.cz, linux-mm@kvack.org List-ID: Christoph Lameter wrote: > On Thu, 26 Jan 2006, Matthew Dobson wrote: > > >>Not all requests for memory from a specific node are performance >>enhancements, some are for correctness. With large machines, especially as > > > alloc_pages_node and friends do not guarantee allocation on that specific > node. That argument for "correctness" is bogus. alloc_pages_node() does not guarantee allocation on a specific node, but calling __alloc_pages() with a specific nodelist would. >>>You do not need this.... >> >>I do not agree... > > > There is no way that you would need this patch. My goal was to not change the behavior of the slab allocator when inserting a mempool-backed allocator "under" it. Without support for at least *requesting* allocations from a specific node when allocating from a mempool, this would change how the slab allocator works. That would be bad. The slab allocator now does not guarantee that, for example, a kmalloc_node() request is satisfied by memory from the requested node, but it does at least TRY. Without adding mempool_alloc_node() then I would never be able to even TRY to satisfy a mempool-backed kmalloc_node() request from the correct node. I believe that would constitute an unacceptable breakage from normal, documented behavior. So, I *do* need this patch. -Matt -- 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