From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933455AbcBYSc4 (ORCPT ); Thu, 25 Feb 2016 13:32:56 -0500 Received: from mx1.redhat.com ([209.132.183.28]:43485 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933151AbcBYScz (ORCPT ); Thu, 25 Feb 2016 13:32:55 -0500 Message-ID: <1456425170.15821.77.camel@redhat.com> Subject: Re: [PATCH 1/1] mm: thp: Redefine default THP defrag behaviour disable it by default From: Rik van Riel To: Mel Gorman , Andrew Morton Cc: Vlastimil Babka , Johannes Weiner , Andrea Arcangeli , Linux-MM , LKML Date: Thu, 25 Feb 2016 13:32:50 -0500 In-Reply-To: <1456420339-29709-1-git-send-email-mgorman@techsingularity.net> References: <1456420339-29709-1-git-send-email-mgorman@techsingularity.net> Content-Type: multipart/signed; micalg="pgp-sha1"; protocol="application/pgp-signature"; boundary="=-wfZLhNrFCToexneBZVpu" Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --=-wfZLhNrFCToexneBZVpu Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Thu, 2016-02-25 at 17:12 +0000, Mel Gorman wrote: > THP gives impressive gains in some cases but only if they are quickly > available.=C2=A0=C2=A0We're not going to reach the point where they are > completely > free so lets take the costs out of the fast paths finally and defer > the > cost to kswapd, kcompactd and khugepaged where it belongs. >=20 > Signed-off-by: Mel Gorman I agree with your conclusions, but with the caveat that if we do not try to defragment memory for THP at fault time, mlocked programs might not have any opportunity at all to get transparent huge pages. I wonder if we should consider mlock one of the slow paths where we should try to actually take the time to create THPs. Also, we might consider doing THP collapse from the NUMA page migration opportunistically, if there is a free 2MB page available on the destination host. Having said all that ... Acked-by: Rik van Riel --=C2=A0 All rights reversed --=-wfZLhNrFCToexneBZVpu Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iQEcBAABAgAGBQJWz0jSAAoJEM553pKExN6DWfcIAKs0WkO1t2H7QgitHYjRFNde cTMENRWwDaKu/usX+lPFHEw4dq9FGEN2U+LPaiP7FCkfYe3pLeoEoPnceX2p8zmI KbhqX+3vvGyzdn2AXYNdy+GviY5L05Kl+Rkgwa+RLksCiEaDFA4jCBldxwqFkPF4 BqXTZGsHHNuGlZTWuLRkgNGnzTAobN0gaX83LP5TwKQbdTbje6cUanIXzwBpSphE egxk1aehJ82qVXkslV8fYchgEm37pS0dvXf+4QVcpQ2LImNp0iHiX/cY2rjkwkdB 5eWGy4DeVDKw3CEubWLHfzT3y9Jb1B/qflTKMnClPobZzrqcZsKEcj3N635xurU= =x30P -----END PGP SIGNATURE----- --=-wfZLhNrFCToexneBZVpu--