From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail137.messagelabs.com (mail137.messagelabs.com [216.82.249.19]) by kanga.kvack.org (Postfix) with ESMTP id 2DD2D6B01A9 for ; Thu, 14 May 2009 08:05:03 -0400 (EDT) Subject: Re: [PATCH] Physical Memory Management [0/1] From: Peter Zijlstra In-Reply-To: References: <20090513151142.5d166b92.akpm@linux-foundation.org> <1242300002.6642.1091.camel@laptop> Content-Type: text/plain; charset="UTF-8" Date: Thu, 14 May 2009 14:05:02 +0200 Message-Id: <1242302702.6642.1140.camel@laptop> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org To: =?UTF-8?Q?Micha=C5=82?= Nazarewicz Cc: Andrew Morton , linux-kernel@vger.kernel.org, m.szyprowski@samsung.com, kyungmin.park@samsung.com, linux-mm@kvack.org List-ID: On Thu, 2009-05-14 at 13:48 +0200, MichaA? Nazarewicz wrote: > > On Thu, 2009-05-14 at 11:00 +0200, MichaA? 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. And who says your pre-allocated pool won't fragment with repeated PMM use? -- 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