From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752101AbbCZJj5 (ORCPT ); Thu, 26 Mar 2015 05:39:57 -0400 Received: from mx1.redhat.com ([209.132.183.28]:41945 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750845AbbCZJjy (ORCPT ); Thu, 26 Mar 2015 05:39:54 -0400 From: Vitaly Kuznetsov To: KY Srinivasan Cc: Haiyang Zhang , "devel\@linuxdriverproject.org" , "linux-kernel\@vger.kernel.org" , Dexuan Cui Subject: Re: [PATCH 0/1] Drivers: hv: hv_balloon: do not online pages in offline blocks References: <1427306520-32463-1-git-send-email-vkuznets@redhat.com> Date: Thu, 26 Mar 2015 10:39:50 +0100 In-Reply-To: (KY Srinivasan's message of "Wed, 25 Mar 2015 18:31:03 +0000") Message-ID: <877fu4rtax.fsf@vitty.brq.redhat.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org KY Srinivasan writes: >> -----Original Message----- >> From: Vitaly Kuznetsov [mailto:vkuznets@redhat.com] >> Sent: Wednesday, March 25, 2015 11:02 AM >> To: KY Srinivasan >> Cc: Haiyang Zhang; devel@linuxdriverproject.org; linux- >> kernel@vger.kernel.org; Dexuan Cui >> Subject: [PATCH 0/1] Drivers: hv: hv_balloon: do not online pages in offline >> blocks >> >> Patch 1/1 is rather a hackaround. The root cause of the issue is the fact that >> we're adding not fully backed memory blocks and allow to online them. It is >> relatively easy to forbid that and add only fully backed 128Mb regions. The >> whole >> driver code will be much simpler: hv_bring_pgs_online() and >> hv_online_page() >> will go away, ha_region_mutex won't probably be required,... Please let me >> know >> if you think I should follow this way. > > Vitaly, > > The main issue I had to address here was that Windows has a 2M alignment for memory > hot add while Linux has a 128M alignment requirement. Furthermore, we will also have to deal with > the case where only a partial 128MB block might be hot-added. The strategy I chose of selectively > onlining pages in a properly aligned block that would be hot added was > to address the above two issues. Yes, we can keep things this was, basically everyhting works. I just wanted to highlight the other possible solution for the issue which is also a major simplification for the driver. So what do you think about my patch? We definitely should avoid onlining pages in offline blocks. > > Regards, > > K. Y >> >> Vitaly Kuznetsov (1): >> Drivers: hv: hv_balloon: do not online pages in offline blocks >> >> drivers/hv/hv_balloon.c | 12 +++++++++++- >> 1 file changed, 11 insertions(+), 1 deletion(-) >> >> -- >> 1.9.3 -- Vitaly