From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx102.postini.com [74.125.245.102]) by kanga.kvack.org (Postfix) with SMTP id 8B72E6B0002 for ; Sun, 3 Mar 2013 21:14:39 -0500 (EST) Received: from mail47-db9 (localhost [127.0.0.1]) by mail47-db9-R.bigfish.com (Postfix) with ESMTP id 331591800ED for ; Mon, 4 Mar 2013 02:14:08 +0000 (UTC) From: KY Srinivasan Subject: RE: [PATCH 1/1] mm: Export split_page(). Date: Mon, 4 Mar 2013 02:14:02 +0000 Message-ID: <3a362e994ab64efda79ae3c80342db95@SN2PR03MB061.namprd03.prod.outlook.com> References: <1362364075-14564-1-git-send-email-kys@microsoft.com> <20130304020747.GA8265@kroah.com> In-Reply-To: <20130304020747.GA8265@kroah.com> Content-Language: en-US Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Sender: owner-linux-mm@kvack.org List-ID: To: Greg KH Cc: "linux-kernel@vger.kernel.org" , "devel@linuxdriverproject.org" , "olaf@aepfle.de" , "apw@canonical.com" , "andi@firstfloor.org" , "akpm@linux-foundation.org" , "linux-mm@kvack.org" > -----Original Message----- > From: Greg KH [mailto:gregkh@linuxfoundation.org] > Sent: Sunday, March 03, 2013 9:08 PM > To: KY Srinivasan > Cc: linux-kernel@vger.kernel.org; devel@linuxdriverproject.org; olaf@aepf= le.de; > apw@canonical.com; andi@firstfloor.org; akpm@linux-foundation.org; linux- > mm@kvack.org > Subject: Re: [PATCH 1/1] mm: Export split_page(). >=20 > On Sun, Mar 03, 2013 at 06:27:55PM -0800, K. Y. Srinivasan wrote: > > The split_page() function will be very useful for balloon drivers. On H= yper-V, > > it will be very efficient to use 2M allocations in the guest as this (a= ) makes > > the ballooning protocol with the host that much more efficient and (b) = moving > > memory in 2M chunks minimizes fragmentation in the host. Export the > split_page() > > function to let the guest allocations be in 2M chunks while the host is= free to > > return this memory at arbitrary granularity. > > > > > > Signed-off-by: K. Y. Srinivasan > > --- > > mm/page_alloc.c | 1 + > > 1 files changed, 1 insertions(+), 0 deletions(-) > > > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > > index 6cacfee..7e0ead6 100644 > > --- a/mm/page_alloc.c > > +++ b/mm/page_alloc.c > > @@ -1404,6 +1404,7 @@ void split_page(struct page *page, unsigned int o= rder) > > for (i =3D 1; i < (1 << order); i++) > > set_page_refcounted(page + i); > > } > > +EXPORT_SYMBOL_GPL(split_page); >=20 > When you export a symbol, you also need to post the code that is going > to use that symbol, otherwise people don't really know how to judge this > request. >=20 > Can you just make this a part of your balloon driver update patch series > instead? Fair enough; I was hoping to see how inclined the mm folks were with regard= s to exporting this symbol before I went ahead and modified the balloon driver c= ode to leverage this. Looking at the Windows guests on Hyper-V, I am convinced 2M = balloon allocations in the Linux (Hyper-V) balloon driver will make significant dif= ference. As you suggest, I will post this patch as part of the balloon driver changes that = use this exported symbol. I am still hoping to get some feedback from the mm guys on this. Regards, K. Y -- 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