From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752082AbbFZNPH (ORCPT ); Fri, 26 Jun 2015 09:15:07 -0400 Received: from smtp02.citrix.com ([66.165.176.63]:20897 "EHLO SMTP02.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751790AbbFZNPA (ORCPT ); Fri, 26 Jun 2015 09:15:00 -0400 X-IronPort-AV: E=Sophos;i="5.13,684,1427760000"; d="scan'208";a="278892602" Message-ID: <558D5050.10103@citrix.com> Date: Fri, 26 Jun 2015 14:14:56 +0100 From: David Vrabel User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Icedove/31.4.0 MIME-Version: 1.0 To: Daniel Kiper , David Vrabel CC: , Boris Ostrovsky , , Subject: Re: [Xen-devel] [PATCHv1 6/8] xen/balloon: only hotplug additional memory if required References: <1435252263-31952-1-git-send-email-david.vrabel@citrix.com> <1435252263-31952-7-git-send-email-david.vrabel@citrix.com> <20150625211834.GO14050@olila.local.net-space.pl> <558D13BF.9030907@citrix.com> <20150626124644.GS14050@olila.local.net-space.pl> In-Reply-To: <20150626124644.GS14050@olila.local.net-space.pl> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 8bit X-DLP: MIA1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 26/06/15 13:46, Daniel Kiper wrote: > On Fri, Jun 26, 2015 at 09:56:31AM +0100, David Vrabel wrote: >> On 25/06/15 22:18, Daniel Kiper wrote: >>> On Thu, Jun 25, 2015 at 06:11:01PM +0100, David Vrabel wrote: >>>> Now that we track the total number of pages (included hotplugged >>>> regions), it is easy to determine if more memory needs to be >>>> hotplugged. >>>> >>>> Signed-off-by: David Vrabel >>>> --- >>>> drivers/xen/balloon.c | 16 +++++++++++++--- >>>> 1 file changed, 13 insertions(+), 3 deletions(-) >>>> >>>> diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c >>>> index 960ac79..dd41da8 100644 >>>> --- a/drivers/xen/balloon.c >>>> +++ b/drivers/xen/balloon.c >>>> @@ -241,12 +241,22 @@ static void release_memory_resource(struct resource *resource) >>>> * bit set). Real size of added memory is established at page onlining stage. >>>> */ >>>> >>>> -static enum bp_state reserve_additional_memory(long credit) >>>> +static enum bp_state reserve_additional_memory(void) >>>> { >>>> + long credit; >>>> struct resource *resource; >>>> int nid, rc; >>>> unsigned long balloon_hotplug; >>>> >>>> + credit = balloon_stats.target_pages - balloon_stats.total_pages; >>>> + >>>> + /* >>>> + * Already hotplugged enough pages? Wait for them to be >>>> + * onlined. >>>> + */ >>> >>> Comment is wrong or at least misleading. Both values does not depend on onlining. >> >> If we get here and credit <=0 then the balloon is empty and we have > > Right. > >> already hotplugged enough sections to reach target. We need to wait for > > OK. > >> userspace to online the sections that already exist. > > This is not true. You do not need to online sections to reserve new > memory region. Onlining does not change balloon_stats.target_pages > nor balloon_stats.total_pages. You must increase balloon_stats.target_pages > above balloon_stats.total_pages to reserve new memory region. And > balloon_stats.target_pages increase is not related to onlining. We don't want to keep adding sections if onlining the existing ones would be sufficient to reach the target. David