From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751659AbdGaGzO (ORCPT ); Mon, 31 Jul 2017 02:55:14 -0400 Received: from mx2.suse.de ([195.135.220.15]:52486 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750877AbdGaGzN (ORCPT ); Mon, 31 Jul 2017 02:55:13 -0400 Date: Mon, 31 Jul 2017 08:55:09 +0200 From: Michal Hocko To: Wei Wang Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, virtualization@lists.linux-foundation.org, mst@redhat.com, mawilcox@microsoft.com, dave.hansen@intel.com, akpm@linux-foundation.org, zhenwei.pi@youruncloud.com Subject: Re: [PATCH] mm: don't zero ballooned pages Message-ID: <20170731065508.GE13036@dhcp22.suse.cz> References: <1501474413-21580-1-git-send-email-wei.w.wang@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1501474413-21580-1-git-send-email-wei.w.wang@intel.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon 31-07-17 12:13:33, Wei Wang wrote: > Ballooned pages will be marked as MADV_DONTNEED by the hypervisor and > shouldn't be given to the host ksmd to scan. Could you point me where this MADV_DONTNEED is done, please? > Therefore, it is not > necessary to zero ballooned pages, which is very time consuming when > the page amount is large. The ongoing fast balloon tests show that the > time to balloon 7G pages is increased from ~491ms to 2.8 seconds with > __GFP_ZERO added. So, this patch removes the flag. Please make it obvious that this is a revert of bb01b64cfab7 ("mm/balloon_compaction.c: enqueue zero page to balloon device"). > Signed-off-by: Wei Wang > --- > mm/balloon_compaction.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/balloon_compaction.c b/mm/balloon_compaction.c > index 9075aa5..b06d9fe 100644 > --- a/mm/balloon_compaction.c > +++ b/mm/balloon_compaction.c > @@ -24,7 +24,7 @@ struct page *balloon_page_enqueue(struct balloon_dev_info *b_dev_info) > { > unsigned long flags; > struct page *page = alloc_page(balloon_mapping_gfp_mask() | > - __GFP_NOMEMALLOC | __GFP_NORETRY | __GFP_ZERO); > + __GFP_NOMEMALLOC | __GFP_NORETRY); > if (!page) > return NULL; > > -- > 2.7.4 > -- Michal Hocko SUSE Labs