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 851E76B01E5 for ; Thu, 14 May 2009 13:10:08 -0400 (EDT) Subject: Re: [PATCH] Physical Memory Management [0/1] From: Peter Zijlstra In-Reply-To: <20090514100718.d8c20b64.akpm@linux-foundation.org> References: <20090513151142.5d166b92.akpm@linux-foundation.org> <1242300002.6642.1091.camel@laptop> <1242302702.6642.1140.camel@laptop> <20090514100718.d8c20b64.akpm@linux-foundation.org> Content-Type: text/plain Date: Thu, 14 May 2009 19:10:00 +0200 Message-Id: <1242321000.6642.1456.camel@laptop> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Andrew Morton Cc: Micha__ Nazarewicz , 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 10:07 -0700, Andrew Morton wrote: > On Thu, 14 May 2009 15:04:55 +0200 > Micha__ Nazarewicz wrote: > > > On Thu, 14 May 2009 14:05:02 +0200, Peter Zijlstra wrote: > > > And who says your pre-allocated pool won't fragment with repeated PMM > > > use? > > > > Yes, this is a good question. What's more, there's no good answer. ;) > > > > We do have capability in page reclaim to deliberately free up > physically contiguous pages (known as "lumpy reclaim"). > > It would be interesting were someone to have a go at making that > available to userspace: ask the kernel to give you 1MB of physically > contiguous memory. There are reasons why this can fail, but migrating > pages can be used to improve the success rate, and userspace can be > careful to not go nuts using mlock(), etc. > > The returned memory would of course need to be protected from other > reclaim/migration/etc activity. I thought we already exposed this, its called hugetlbfs ;-) -- 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