From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752094AbeFDR5f (ORCPT ); Mon, 4 Jun 2018 13:57:35 -0400 Received: from shelob.surriel.com ([96.67.55.147]:53658 "EHLO shelob.surriel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751824AbeFDR5c (ORCPT ); Mon, 4 Jun 2018 13:57:32 -0400 Message-ID: <1528135046.7898.111.camel@surriel.com> Subject: Re: [PATCH 10/19] sched/numa: Stop multiple tasks from moving to the cpu at the same time From: Rik van Riel To: Srikar Dronamraju , Ingo Molnar , Peter Zijlstra Cc: LKML , Mel Gorman , Thomas Gleixner Date: Mon, 04 Jun 2018 13:57:26 -0400 In-Reply-To: <1528106428-19992-11-git-send-email-srikar@linux.vnet.ibm.com> References: <1528106428-19992-1-git-send-email-srikar@linux.vnet.ibm.com> <1528106428-19992-11-git-send-email-srikar@linux.vnet.ibm.com> Content-Type: multipart/signed; micalg="pgp-sha256"; protocol="application/pgp-signature"; boundary="=-NxKfD/2Y+rhlAfibarDd" X-Mailer: Evolution 3.26.6 (3.26.6-1.fc27) Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --=-NxKfD/2Y+rhlAfibarDd Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Mon, 2018-06-04 at 15:30 +0530, Srikar Dronamraju wrote: > Task migration under numa balancing can happen in parallel. More than > one task might choose to migrate to the same cpu at the same time. > This > can result in > - During task swap, choosing a task that was not part of the > evaluation. > - During task swap, task which just got moved into its preferred > node, > moving to a completely different node. > - During task swap, task failing to move to the preferred node, will > have > to wait an extra interval for the next migrate opportunity. > - During task movement, multiple task movements can cause load > imbalance. >=20 > This problem is more likely if there are more cores per node or more > nodes in the system. >=20 > Use a per run-queue variable to check if numa-balance is active on > the > run-queue. > Signed-off-by: Srikar Dronamraju >=20 Reviewed-by: Rik van Riel --=20 All Rights Reversed. --=-NxKfD/2Y+rhlAfibarDd Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- iQEzBAABCAAdFiEEKR73pCCtJ5Xj3yADznnekoTE3oMFAlsVfYYACgkQznnekoTE 3oORwQf9HinMxuLzwEr+rQosWD7nhA08dAWtHbKMtJw+HJqs254cIKwjb54vqzgz POShG1qGKkEis34DSfiVwFH+SCIvBPrOFK0kBR4Jg7diu26Rv+QrdMnxSASvZNlr hd41tMxCzEkPrdfh0hRwI1j4DFRprChJnQ33PWAjGEkyN4YPYdt+pS09hcURkFIZ Vu5JU7UmtSM2gePkHQiQ2eNdTOzvQUUjuKZPWThkJpv6KJKt9xgn2MYmIjqMsRj9 iKom7sP7O7ArvWVaQd5MN2Fdp5k6CkFyX2ObMGXeQSSrDE8+gA8jxQAl1M3+dBvm 68IHC1qeYQmM+HQmx4Ty6xGf6thiKA== =zGt/ -----END PGP SIGNATURE----- --=-NxKfD/2Y+rhlAfibarDd--