From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from pic75-3-78-194-244-226.fbxo.proxad.net ([78.194.244.226]:54938 "EHLO mail.corsac.net" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1751843AbeAHRVo (ORCPT ); Mon, 8 Jan 2018 12:21:44 -0500 Received: from scapa.corsac.net (unknown [IPv6:2a01:e34:ec2f:4e21::1]) by mail.corsac.net (Postfix) with ESMTPS id 92AE68F for ; Mon, 8 Jan 2018 18:21:42 +0100 (CET) Message-ID: <1515432097.3305.66.camel@debian.org> Subject: Re: Feedback on 4.9 performance after PTI fixes From: Yves-Alexis Perez To: Willy Tarreau , linux-kernel@vger.kernel.org, stable@vger.kernel.org Date: Mon, 08 Jan 2018 18:21:37 +0100 In-Reply-To: <1515431274.3305.59.camel@debian.org> References: <20180107101856.GA9590@1wt.eu> <1515431274.3305.59.camel@debian.org> Content-Type: multipart/signed; micalg="pgp-sha256"; protocol="application/pgp-signature"; boundary="=-HGaSvX9tKzeC+wfFUuz/" Mime-Version: 1.0 Sender: stable-owner@vger.kernel.org List-ID: --=-HGaSvX9tKzeC+wfFUuz/ Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Mon, 2018-01-08 at 18:07 +0100, Yves-Alexis Perez wrote: > On Sun, 2018-01-07 at 11:18 +0100, Willy Tarreau wrote: > > - the highest performance impact on VMs comes from having PTI on the > > guest kernel (-45%). At this point it makes no difference whether > > the host kernel has it or not. >=20 > Hi Willy, >=20 > out of curiosity, is the pcid/invpcid flags exposed to and used by your g= uest > CPU? It might very well that the PCID optimisations are not used by the g= uests > here, and it might be worth either checking on bare metal or with the PCI= D > optimisations enabled. More details on this: https://groups.google.com/forum/m/#!topic/mechanical-= sympathy/L9mHTbeQLNU Regards, --=20 Yves-Alexis --=-HGaSvX9tKzeC+wfFUuz/ Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part -----BEGIN PGP SIGNATURE----- iQEzBAABCAAdFiEE8vi34Qgfo83x35gF3rYcyPpXRFsFAlpTqKEACgkQ3rYcyPpX RFu0xgf/frD/jW+nN0H6mUbC+AKPNOo9pWncNGkcfPHmZ+TIAeFtbwkLUehZ9CDg bae8Npo48TKNFkDGDFKsoM0LDRDvtJSU+yZElJlMXHC8zDSIts8J1eBv2spirV10 Ck2BORJeQjEjwgaBWU6seUW4sPtLKUEWjXdos1ipFbjzmiOculZurvfyxHHUCpkW qvR3dof72/EXX+IhygVAjlhZnFOStiSv3pge/bCsJ7So/vxBYKBf6cUQDLK/MS5u MBOSmLk4RE50ED0Zoh3RYmBGsWYxem9DNdciUxo7S4GVrzabGa+Kdmv0oW5T8lkb mjZx9IwwjH/edekFeb2wYVwzBdvqRw== =aRNH -----END PGP SIGNATURE----- --=-HGaSvX9tKzeC+wfFUuz/--