From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760791AbZENLtR (ORCPT ); Thu, 14 May 2009 07:49:17 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1760642AbZENLst (ORCPT ); Thu, 14 May 2009 07:48:49 -0400 Received: from mailout1.w1.samsung.com ([210.118.77.11]:29158 "EHLO mailout1.w1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760616AbZENLss (ORCPT ); Thu, 14 May 2009 07:48:48 -0400 Date: Thu, 14 May 2009 13:48:39 +0200 From: =?utf-8?B?TWljaGHFgiBOYXphcmV3aWN6?= Subject: Re: [PATCH] Physical Memory Management [0/1] In-reply-to: <1242300002.6642.1091.camel@laptop> To: Peter Zijlstra Cc: Andrew Morton , linux-kernel@vger.kernel.org, m.szyprowski@samsung.com, kyungmin.park@samsung.com, linux-mm@kvack.org Message-id: Organization: Samsung Electronics MIME-version: 1.0 Content-type: text/plain; charset=utf-8 Content-transfer-encoding: 8BIT User-Agent: Opera Mail/10.00 (Win32) References: <20090513151142.5d166b92.akpm@linux-foundation.org> <1242300002.6642.1091.camel@laptop> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > On Thu, 2009-05-14 at 11:00 +0200, Michał Nazarewicz wrote: >> PMM solves this problem since the buffers are allocated when they >> are needed. On Thu, 14 May 2009 13:20:02 +0200, Peter Zijlstra wrote: > Ha - only when you actually manage to allocate things. Physically > contiguous allocations are exceedingly hard once the machine has been > running for a while. PMM reserves memory during boot time using alloc_bootmem_low_pages(). After this is done, it can allocate buffers from reserved pool. The idea here is that there are n hardware accelerators, each can operate on 1MiB blocks (to simplify assume that's the case). However, we know that at most m < n devices will be used at the same time so instead of reserving n MiBs of memory we reserve only m MiBs. -- Best regards, _ _ .o. | Liege of Serenly Enlightened Majesty of o' \,=./ `o ..o | Computer Science, Michał "mina86" Nazarewicz (o o) ooo +---ooO--(_)--Ooo--