From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dario Faggioli Subject: Re: [PATCH 2/2] xen: sched: we never get into context_switch() with prev==next Date: Fri, 26 Apr 2019 17:13:50 +0200 Message-ID: References: <155577364571.25746.11988517450711182732.stgit@wayrath> <155577388740.25746.3780283868034526234.stgit@wayrath> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============7195325543815925688==" Return-path: Received: from us1-rack-dfw2.inumbo.com ([104.130.134.6]) by lists.xenproject.org with esmtp (Exim 4.89) (envelope-from ) id 1hK3G9-0003NL-UR for xen-devel@lists.xenproject.org; Fri, 26 Apr 2019 15:59:33 +0000 In-Reply-To: List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" To: Andrii Anisov , xen-devel@lists.xenproject.org Cc: Juergen Gross , Stefano Stabellini , Wei Liu , Andrew Cooper , George Dunlap , Julien Grall , Jan Beulich , Roger Pau =?ISO-8859-1?Q?Monn=E9?= List-Id: xen-devel@lists.xenproject.org --===============7195325543815925688== Content-Type: multipart/signed; micalg="pgp-sha256"; protocol="application/pgp-signature"; boundary="=-Qya4sY0pOsb5RKC9AF51" --=-Qya4sY0pOsb5RKC9AF51 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Tue, 2019-04-23 at 12:13 +0300, Andrii Anisov wrote: > Hello Dario, >=20 > On 20.04.19 18:24, Dario Faggioli wrote: > > In schedule(), if we pick, as the next vcpu to run (next) the same > > one > > that is running already (prev), we never get to call > > context_switch(). >=20 > And what about `if ( prev !=3D current )` in > arm/domain.c:schedule_tail() ? >=20 You're suggesting that's redundant too, aren't you? =46rom a quick look, it seems to me as well that it would be. I'm ok taking care of it, not sure if in this patch, or in another one. I'm open to suggestions from ARM maintainers... 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) --=-Qya4sY0pOsb5RKC9AF51 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part -----BEGIN PGP SIGNATURE----- iQIzBAABCAAdFiEES5ssOj3Vhr0WPnOLFkJ4iaW4c+4FAlzDIBEACgkQFkJ4iaW4 c+62sw/9EGBfsTcE7wmc64VwHDbpoYxfFhkL0YMuZB3yeZefV0EWIY4Ok3kzVOYu hBMSlJW9LsllUBzAxTRWVPFsFWqo7/HjoJ1PkpBJSzwElIq/VEvH3//MzLwdD35v 7fND8ytY4NA+N55SAPsX0sQqA21/C2LfqlbguWu4+tL32mzkDyYtLlE+5+wAAiNB ZnapmikiIn7LFfdYQ9kxseyioZWeF35msEKVeq/sIw6tQgxkK1j+00sSQxpqBGW2 jAAOwoTt4ybTnKhGCBLiCwYjZ45fQh+ZO4wGTIJku4Rkq8u2uLZIxh3tRWjmmC0s G1UAXH/yiRGK3ipYK6YmBGvCNyntTDsDyNRNKSp6wqG65muXuoCB9ZqHmjQ+XnpL ZA4a1fD2Vf2RR601hNXBqmhTGIuiMpq2fVIDMCYzCObra7kK3BkAtbmUC7e7eohG mkqOOGUsRXo0iwzLpaklFSKJ44yj/3yFefzU6LEeBRLVY2yK60gMN1a0qg07Z05Q fTgVtvaG9UcBYx95p6aldimGlGBj9h4liB/IHefIYjCx5lAdgoLA7rHTOBpYjLhF JMB4BYmIqDCmLLE+ircGZf/tWmfw7YP9ZZarg47UPBUzeNR4bp8/hFBD1a8PuSEy fOmsIykoOizycBb5yCD+fmvev//4mz636CNgLwMQEc6XRW/KifQ= =HVcJ -----END PGP SIGNATURE----- --=-Qya4sY0pOsb5RKC9AF51-- --===============7195325543815925688== Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: base64 Content-Disposition: inline X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX18KWGVuLWRldmVs IG1haWxpbmcgbGlzdApYZW4tZGV2ZWxAbGlzdHMueGVucHJvamVjdC5vcmcKaHR0cHM6Ly9saXN0 cy54ZW5wcm9qZWN0Lm9yZy9tYWlsbWFuL2xpc3RpbmZvL3hlbi1kZXZlbA== --===============7195325543815925688==-- 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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 11C3BC43218 for ; Fri, 26 Apr 2019 15:59:55 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id DCADF2077B for ; 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Fri, 26 Apr 2019 17:59:29 +0200 Received: from [192.168.0.30] (nwb-a10-snat.microfocus.com [10.120.13.202]) by emea4-mta.ukb.novell.com with ESMTP (TLS encrypted); Fri, 26 Apr 2019 16:59:02 +0100 Message-ID: From: Dario Faggioli To: Andrii Anisov , xen-devel@lists.xenproject.org In-Reply-To: References: <155577364571.25746.11988517450711182732.stgit@wayrath> <155577388740.25746.3780283868034526234.stgit@wayrath> Organization: SUSE MIME-Version: 1.0 Date: Fri, 26 Apr 2019 17:13:50 +0200 User-Agent: Evolution 3.30.5 Subject: Re: [Xen-devel] [PATCH 2/2] xen: sched: we never get into context_switch() with prev==next X-BeenThere: xen-devel@lists.xenproject.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Cc: Juergen Gross , Stefano Stabellini , Wei Liu , Andrew Cooper , George Dunlap , Julien Grall , Jan Beulich , Roger Pau =?ISO-8859-1?Q?Monn=E9?= Content-Type: multipart/mixed; boundary="===============7195325543815925688==" Errors-To: xen-devel-bounces@lists.xenproject.org Sender: "Xen-devel" Message-ID: <20190426151350.LjarNrwtK-K9nTtr3aOFzPFBbCt2BrNYUwKD_ezZojM@z> --===============7195325543815925688== Content-Type: multipart/signed; micalg="pgp-sha256"; protocol="application/pgp-signature"; boundary="=-Qya4sY0pOsb5RKC9AF51" --=-Qya4sY0pOsb5RKC9AF51 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Tue, 2019-04-23 at 12:13 +0300, Andrii Anisov wrote: > Hello Dario, >=20 > On 20.04.19 18:24, Dario Faggioli wrote: > > In schedule(), if we pick, as the next vcpu to run (next) the same > > one > > that is running already (prev), we never get to call > > context_switch(). >=20 > And what about `if ( prev !=3D current )` in > arm/domain.c:schedule_tail() ? >=20 You're suggesting that's redundant too, aren't you? =46rom a quick look, it seems to me as well that it would be. I'm ok taking care of it, not sure if in this patch, or in another one. I'm open to suggestions from ARM maintainers... 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) --=-Qya4sY0pOsb5RKC9AF51 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part -----BEGIN PGP SIGNATURE----- iQIzBAABCAAdFiEES5ssOj3Vhr0WPnOLFkJ4iaW4c+4FAlzDIBEACgkQFkJ4iaW4 c+62sw/9EGBfsTcE7wmc64VwHDbpoYxfFhkL0YMuZB3yeZefV0EWIY4Ok3kzVOYu hBMSlJW9LsllUBzAxTRWVPFsFWqo7/HjoJ1PkpBJSzwElIq/VEvH3//MzLwdD35v 7fND8ytY4NA+N55SAPsX0sQqA21/C2LfqlbguWu4+tL32mzkDyYtLlE+5+wAAiNB ZnapmikiIn7LFfdYQ9kxseyioZWeF35msEKVeq/sIw6tQgxkK1j+00sSQxpqBGW2 jAAOwoTt4ybTnKhGCBLiCwYjZ45fQh+ZO4wGTIJku4Rkq8u2uLZIxh3tRWjmmC0s G1UAXH/yiRGK3ipYK6YmBGvCNyntTDsDyNRNKSp6wqG65muXuoCB9ZqHmjQ+XnpL ZA4a1fD2Vf2RR601hNXBqmhTGIuiMpq2fVIDMCYzCObra7kK3BkAtbmUC7e7eohG mkqOOGUsRXo0iwzLpaklFSKJ44yj/3yFefzU6LEeBRLVY2yK60gMN1a0qg07Z05Q fTgVtvaG9UcBYx95p6aldimGlGBj9h4liB/IHefIYjCx5lAdgoLA7rHTOBpYjLhF JMB4BYmIqDCmLLE+ircGZf/tWmfw7YP9ZZarg47UPBUzeNR4bp8/hFBD1a8PuSEy fOmsIykoOizycBb5yCD+fmvev//4mz636CNgLwMQEc6XRW/KifQ= =HVcJ -----END PGP SIGNATURE----- --=-Qya4sY0pOsb5RKC9AF51-- --===============7195325543815925688== Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: base64 Content-Disposition: inline X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX18KWGVuLWRldmVs IG1haWxpbmcgbGlzdApYZW4tZGV2ZWxAbGlzdHMueGVucHJvamVjdC5vcmcKaHR0cHM6Ly9saXN0 cy54ZW5wcm9qZWN0Lm9yZy9tYWlsbWFuL2xpc3RpbmZvL3hlbi1kZXZlbA== --===============7195325543815925688==--