From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail172.messagelabs.com (mail172.messagelabs.com [216.82.254.3]) by kanga.kvack.org (Postfix) with ESMTP id 214608D003B for ; Thu, 10 Mar 2011 03:52:21 -0500 (EST) Received: (from localhost user: 'dkiper' uid#4000 fake: STDIN (dkiper@router-fw.net-space.pl)) by router-fw-old.local.net-space.pl id S1579637Ab1CJIvg (ORCPT ); Thu, 10 Mar 2011 09:51:36 +0100 Date: Thu, 10 Mar 2011 09:51:36 +0100 From: Daniel Kiper Subject: Re: [PATCH R4 6/7] mm: Extend memory hotplug API to allow memory hotplug in virtual guests Message-ID: <20110310085136.GA13978@router-fw-old.local.net-space.pl> References: <20110308215003.GG27331@router-fw-old.local.net-space.pl> <1299628272.9014.3465.camel@nimitz> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1299628272.9014.3465.camel@nimitz> Sender: owner-linux-mm@kvack.org List-ID: To: Dave Hansen Cc: Daniel Kiper , ian.campbell@citrix.com, akpm@linux-foundation.org, andi.kleen@intel.com, haicheng.li@linux.intel.com, fengguang.wu@intel.com, jeremy@goop.org, konrad.wilk@oracle.com, dan.magenheimer@oracle.com, v.tolstov@selfip.ru, pasik@iki.fi, wdauchy@gmail.com, rientjes@google.com, xen-devel@lists.xensource.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org On Tue, Mar 08, 2011 at 03:51:12PM -0800, Dave Hansen wrote: > On Tue, 2011-03-08 at 22:50 +0100, Daniel Kiper wrote: > > +int add_virtual_memory(u64 *size) > > +{ > > + int nid; > > + u64 start; > > + > > + start = PFN_PHYS(SECTION_ALIGN(max_pfn)); > > + *size = (((*size >> PAGE_SHIFT) & PAGE_SECTION_MASK) + PAGES_PER_SECTION) << PAGE_SHIFT; > > Why use PFN_PHYS() in one case but not the other? I know that this is the same, however, I think PFN_PHYS() usage suggest that I do a PFN/address manipulation. It is not true in that case (I do an operation on region size) and I would like to avoid that ambiguity. > I'd also highly suggest using the ALIGN() macro in cases like this. It > makes it much more readable: OK. > *size = PFN_PHYS(ALIGN(*size, SECTION_SIZE))); > > > + nid = memory_add_physaddr_to_nid(start); > > + > > + return add_memory(nid, start, *size); > > +} > > Could you talk a little bit more about how 'size' gets used? Also, are > we sure we want an interface where we're so liberal with 'size'? It > seems like requiring that it be section-aligned is a fair burden to > place on the caller. That way, we're not in a position of _guessing_ > what the caller wants (aligning up or down). I do not have like this function since I created it. However, I decided to sent it for review. It does not simplify anything (add_memory() as a generic function is sufficient) and it is too inflexible. Now, I am sure that everything in its body should be moved to platform specific module (in that case Xen). I am going to that on next patch release. Daniel -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org