From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7BB9BC433B4 for ; Thu, 22 Apr 2021 16:47:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3DB4961409 for ; Thu, 22 Apr 2021 16:47:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238011AbhDVQro (ORCPT ); Thu, 22 Apr 2021 12:47:44 -0400 Received: from shelob.surriel.com ([96.67.55.147]:35582 "EHLO shelob.surriel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236657AbhDVQrn (ORCPT ); Thu, 22 Apr 2021 12:47:43 -0400 Received: from imladris.surriel.com ([96.67.55.152]) by shelob.surriel.com with esmtpsa (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94) (envelope-from ) id 1lZcTl-00088P-I4; Thu, 22 Apr 2021 12:47:01 -0400 Message-ID: <416c515026af10cc913a83bc72c18aeb296c6583.camel@surriel.com> Subject: Re: [PATCH v3] sched,fair: skip newidle_balance if a wakeup is pending From: Rik van Riel To: Vincent Guittot Cc: linux-kernel , Kernel Team , Peter Zijlstra , Ingo Molnar , Dietmar Eggemann , Mel Gorman , Valentin Schneider Date: Thu, 22 Apr 2021 12:47:01 -0400 In-Reply-To: References: <20210420120705.5c705d4b@imladris.surriel.com> Content-Type: multipart/signed; micalg="pgp-sha256"; protocol="application/pgp-signature"; boundary="=-yCBy0EHXV/dXifHXfKvy" User-Agent: Evolution 3.34.4 (3.34.4-1.fc31) MIME-Version: 1.0 Sender: riel@shelob.surriel.com Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --=-yCBy0EHXV/dXifHXfKvy Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Thu, 2021-04-22 at 10:37 +0200, Vincent Guittot wrote: > On Wed, 21 Apr 2021 at 19:27, Vincent Guittot > wrote: > >=20 > > > - if (pulled_task) > > > + /* > > > + * If we are no longer idle, do not let the time spent > > > here pull > > > + * down this_rq->avg_idle. That could lead to > > > newidle_balance not > > > + * doing enough work, and the CPU actually going idle. > > > + */ > > > + if (pulled_task || this_rq->ttwu_pending) > >=20 > I confirmed that the line above generate hackbench regression on my > large arm64 system (2 * 112 CPUs) > I'm testing hackbench with various number of group : 1, 2, 4, 16, 32, > 64, 128, 256 but I have only put the 2 results which significantly > regress. The other ones are in the +/-1% variation range >=20 > hackbench -g $group >=20 > group v5.12-rc8+tip w/ this patch w/ this patch > without > the line above > 64 2.862(+/- 9%) 2.952(+/-11%) -3% 2.807(+/- 7%) +2% > 128 3.334(+/-10%) 3.561-+/-13%) -7% 3.181(+/- 6%) +4% OK, I guess this part of the patch needs additional work. I'll send a v4 with just the first two changes. Thank you for running those tests. --=20 All Rights Reversed. --=-yCBy0EHXV/dXifHXfKvy Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- iQEzBAABCAAdFiEEKR73pCCtJ5Xj3yADznnekoTE3oMFAmCBqIUACgkQznnekoTE 3oOUmgf/Z/szhtFna60CfwqqA2THsv3i0ehF+f4r1z7Y9HSkk3YSKcdfutPXIUOU kBrkd7+mns5HS8iVsmeIHB6LjyPtfARpqgVWIS9yF+6LWL7mU18yTABwjFFu0wk0 Dgr2SbNkRvTtqin93k4bPvA3FQhH3yx+Zn5+4qt72zy7aJcb9FJTruxQ8PZFctge ApHrxhTvZlFjx9sbakHiVpD6KoCWlJJoa8CNosPsDhZyi8spUNsfUybOb5XR9C5X AS00AcYwzRdKJYAcVptLUv7Nn6ikqVZb/WvG4k7vDok7yXueKKEejcEpoI3MXL76 Ad8UIoASVdzpXD0NlzKP9Yc4f7bihA== =dEQ8 -----END PGP SIGNATURE----- --=-yCBy0EHXV/dXifHXfKvy--