Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751864AbbFYVS7 (ORCPT ); Thu, 25 Jun 2015 17:18:59 -0400 Received: from userp1040.oracle.com ([156.151.31.81]:36910 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750993AbbFYVSx (ORCPT ); Thu, 25 Jun 2015 17:18:53 -0400 Date: Thu, 25 Jun 2015 23:18:34 +0200 From: Daniel Kiper To: David Vrabel Cc: xen-devel@lists.xenproject.org, Konrad Rzeszutek Wilk , Boris Ostrovsky , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCHv1 6/8] xen/balloon: only hotplug additional memory if required Message-ID: <20150625211834.GO14050@olila.local.net-space.pl> References: <1435252263-31952-1-git-send-email-david.vrabel@citrix.com> <1435252263-31952-7-git-send-email-david.vrabel@citrix.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1435252263-31952-7-git-send-email-david.vrabel@citrix.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-Source-IP: userv0022.oracle.com [156.151.31.74] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1823 Lines: 50 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 (credit <= 0) > + return BP_EAGAIN; Not BP_EAGAIN for sure. It should be BP_DONE but then balloon_process() will go into loop until memory is onlined at least up to balloon_stats.target_pages. BP_ECANCELED does work but it is misleading because it is not an error. So, maybe we should introduce BP_STOP (or something like that) which works like BP_ECANCELED and is not BP_ECANCELED. Daniel -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/