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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 3E4F5C3A589 for ; Thu, 15 Aug 2019 16:09:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 19E2720644 for ; Thu, 15 Aug 2019 16:09:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729924AbfHOQJc (ORCPT ); Thu, 15 Aug 2019 12:09:32 -0400 Received: from mx2.suse.de ([195.135.220.15]:55846 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728329AbfHOQJb (ORCPT ); Thu, 15 Aug 2019 12:09:31 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 48CE9AD73; Thu, 15 Aug 2019 16:09:30 +0000 (UTC) Message-ID: Subject: Re: [RFC PATCH v3 00/16] Core scheduling v3 From: Dario Faggioli To: Tim Chen , Julien Desfossez , "Li, Aubrey" Cc: Aaron Lu , Aubrey Li , Subhra Mazumdar , Vineeth Remanan Pillai , Nishanth Aravamudan , Peter Zijlstra , Ingo Molnar , Thomas Gleixner , Paul Turner , Linus Torvalds , Linux List Kernel Mailing , =?ISO-8859-1?Q?Fr=E9d=E9ric?= Weisbecker , Kees Cook , Greg Kerr , Phil Auld , Valentin Schneider , Mel Gorman , Pawan Gupta , Paolo Bonzini Date: Thu, 15 Aug 2019 18:09:28 +0200 In-Reply-To: <69cd9bca-da28-1d35-3913-1efefe0c1c22@linux.intel.com> References: <20190612163345.GB26997@sinkpad> <635c01b0-d8f3-561b-5396-10c75ed03712@oracle.com> <20190613032246.GA17752@sinkpad> <20190619183302.GA6775@sinkpad> <20190718100714.GA469@aaronlu> <20190725143003.GA992@aaronlu> <20190726152101.GA27884@sinkpad> <7dc86e3c-aa3f-905f-3745-01181a3b0dac@linux.intel.com> <20190802153715.GA18075@sinkpad> <69cd9bca-da28-1d35-3913-1efefe0c1c22@linux.intel.com> Organization: SUSE Content-Type: multipart/signed; micalg="pgp-sha256"; protocol="application/pgp-signature"; boundary="=-fKuNyrN5LAubUKk4rsAy" User-Agent: Evolution 3.32.4 MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --=-fKuNyrN5LAubUKk4rsAy Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Wed, 2019-08-07 at 10:10 -0700, Tim Chen wrote: > On 8/7/19 1:58 AM, Dario Faggioli wrote: >=20 > > Since I see that, in this thread, there are various patches being > > proposed and discussed... should I rerun my benchmarks with them > > applied? If yes, which ones? And is there, by any chance, one (or > > maybe > > more than one) updated git branch(es)? > >=20 > Hi Dario, >=20 Hi Tim! > Having an extra set of eyes are certainly welcomed. > I'll give my 2 cents on the issues with v3. >=20 Ok, and thanks a lot for this. > 1) Unfairness between the sibling threads > ----------------------------------------- > One sibling thread could be suppressing and force idling > the sibling thread over proportionally. Resulting in > the force idled CPU not getting run and stall tasks on > suppressed CPU. >=20 >=20 > [...] > > 2) Not rescheduling forced idled CPU > ------------------------------------ > The forced idled CPU does not get a chance to re-schedule > itself, and will stall for a long time even though it > has eligible tasks to run. >=20 > [...] >=20 > 3) Load balancing between CPU cores > ----------------------------------- > Say if one CPU core's sibling threads get forced idled > a lot as it has mostly incompatible tasks between the siblings, > moving the incompatible load to other cores and pulling > compatible load to the core could help CPU utilization. >=20 > So just considering the load of a task is not enough during > load balancing, task compatibility also needs to be considered. > Peter has put in mechanisms to balance compatible tasks between > CPU thread siblings, but not across cores. >=20 > [...] > Ok. Yes, as said, I've been trying to follow the thread, but thanks a lot again for this summary. As said, I'm about to have numbers for the repo/branch I mentioned. I was considering whether to also re-run the benchmarking campaign with some of the patches that floated around within this thread. Now, thanks to your summary, I have an even clearer picture about which patch does what, and that is indeed very useful. I'll see about putting something together. I'm thinking of picking: https://lore.kernel.org/lkml/b7a83fcb-5c34-9794-5688-55c52697fd84@linux.int= el.com/ https://lore.kernel.org/lkml/20190725143344.GD992@aaronlu/ And maybe even (part of): https://lore.kernel.org/lkml/20190810141556.GA73644@aaronlu/#t If anyone has ideas or suggestions about whether or not this choice makes sense, feel free to share. :-) Also, I only have another week before leaving, so let's see what I manage to actually run, and then share here, by then. Thanks and Regards --=20 Dario Faggioli, Ph.D http://about.me/dario.faggioli Virtualization Software Engineer SUSE Labs, SUSE https://www.suse.com/ ------------------------------------------------------------------- <> (Raistlin Majere) --=-fKuNyrN5LAubUKk4rsAy Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- iQIzBAABCAAdFiEES5ssOj3Vhr0WPnOLFkJ4iaW4c+4FAl1Vg7gACgkQFkJ4iaW4 c+7Z7hAAlwTpfoVwhmTyJl3fop1DDwUFulFl/SKmSLk+CkrB5Fc4HHCUNgbyVAfS rE8a9aYjLQYk6Fw0w6EXo6TOwc02tIgTiG3qqeuhgI7XAxMkgsTpT9wDpG+J9qxo eRmws0cNvqx2CU538mAfqgqSIzxTY11ImXLjVf47gJ6Sji5x/+dL7aoNF/Kg6qRd KahZqLSPZwJhskDqqyfUsNdgQleck/cADpR/PGon1nKFgWqYnJWFRtSKVyeDQUML YZiwr2p3XceyhwvMBgSZrg3oOMQHmnVQKp199mk3aXRX2i3A3VU5pMcRh9EsOnaS xHkfJLv59g6PUW9CEyOF7/yfBxJjDyJWodZxXXacJTIS4wTt1WT+jKJa/r+uMqKh sQBl9Thh3BZ40V0nKFxxdza/+KmGpVg8P3mXDSrPzTc91Ci8hxwMnLQJwy+j0CUJ KUNiXCdRgPvDM3qvwMPRADQodDTbLfUe7za2YJBZSdGGIeAaxSCCgN3s6XIPuBKK Qm0sIhqIvWbGK2Sad/5m+xCVNNJkEbmvxm3HiLNfnSaWaLjbCvUSDeoV6U1Iirkj 4N2Urr7QtIa/Nz+bkUsVw06VTgXwmIQMaoYpcPrxmxVrfmRbBi931ox9gPG9FUIy lLL3X2+Wl9c4oS/469UX5ckVyXhL1aOr99TpyJAvpuxuLUDgWmc= =317a -----END PGP SIGNATURE----- --=-fKuNyrN5LAubUKk4rsAy--