From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qk0-f169.google.com (mail-qk0-f169.google.com [209.85.220.169]) by kanga.kvack.org (Postfix) with ESMTP id DCAA46B0253 for ; Thu, 25 Feb 2016 13:32:56 -0500 (EST) Received: by mail-qk0-f169.google.com with SMTP id s5so22891034qkd.0 for ; Thu, 25 Feb 2016 10:32:56 -0800 (PST) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTPS id b107si9186488qge.55.2016.02.25.10.32.55 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 25 Feb 2016 10:32:55 -0800 (PST) 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 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: owner-linux-mm@kvack.org List-ID: To: Mel Gorman , Andrew Morton Cc: Vlastimil Babka , Johannes Weiner , Andrea Arcangeli , Linux-MM , LKML --=-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-- -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org