From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753737AbdCPPB6 (ORCPT ); Thu, 16 Mar 2017 11:01:58 -0400 Received: from mx2.suse.de ([195.135.220.15]:52465 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752793AbdCPPB4 (ORCPT ); Thu, 16 Mar 2017 11:01:56 -0400 Date: Thu, 16 Mar 2017 16:01:53 +0100 From: Michal Hocko To: Avi Kivity Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: MAP_POPULATE vs. MADV_HUGEPAGES Message-ID: <20170316150153.GK30501@dhcp22.suse.cz> References: <20170316123449.GE30508@dhcp22.suse.cz> <4e1011d9-aef3-5cd7-1424-b81aa79128cb@scylladb.com> <20170316144832.GJ30501@dhcp22.suse.cz> <53e8bb71-5bf2-2690-f605-aa4d5d50eb90@scylladb.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <53e8bb71-5bf2-2690-f605-aa4d5d50eb90@scylladb.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 Thu 16-03-17 16:56:34, Avi Kivity wrote: > On 03/16/2017 04:48 PM, Michal Hocko wrote: > >On Thu 16-03-17 15:26:54, Avi Kivity wrote: [...] > >>>What is the THP defrag mode > >>>(/sys/kernel/mm/transparent_hugepage/defrag)? > >>The default (always). > >the default has changed since then because the THP faul latencies were > >just too large. Currently we only allow madvised VMAs to go stall and > >even then we try hard to back off sooner rather than later. See > >444eb2a449ef ("mm: thp: set THP defrag by default to madvise and add a > >stall-free defrag option") merged in 4.4 > > I see, thanks. So the 4.4 behavior is better mostly due to not trying so > hard. Please note there were many other patches in the compaction code as well. -- Michal Hocko SUSE Labs