Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935602AbeAHRID (ORCPT + 1 other); Mon, 8 Jan 2018 12:08:03 -0500 Received: from pic75-3-78-194-244-226.fbxo.proxad.net ([78.194.244.226]:54766 "EHLO mail.corsac.net" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S934630AbeAHRIB (ORCPT ); Mon, 8 Jan 2018 12:08:01 -0500 Message-ID: <1515431274.3305.59.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 18:07:54 +0100 In-Reply-To: <20180107101856.GA9590@1wt.eu> References: <20180107101856.GA9590@1wt.eu> Content-Type: multipart/signed; micalg="pgp-sha256"; protocol="application/pgp-signature"; boundary="=-rgItgkzTV0zO7tkNlmZO" X-Mailer: Evolution 3.26.3-1 Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: --=-rgItgkzTV0zO7tkNlmZO Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable 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. Hi Willy, out of curiosity, is the pcid/invpcid flags exposed to and used by your gue= st CPU? It might very well that the PCID optimisations are not used by the gue= sts here, and it might be worth either checking on bare metal or with the PCID optimisations enabled. Regards, --=20 Yves-Alexis --=-rgItgkzTV0zO7tkNlmZO Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part -----BEGIN PGP SIGNATURE----- iQEzBAABCAAdFiEE8vi34Qgfo83x35gF3rYcyPpXRFsFAlpTpWoACgkQ3rYcyPpX RFtWaAf/bh3asU+S2AuFYRbJRtt3G62K2VvgN8xDRp5tQfcmvTtkFbkbWW+mXX5R PvwFA4P13sAdx5yFgFbgPy5vWQvMv6e4qRrhpHC7WaqJMKztClpCXP8EvtPxVYwQ 8nnEriAdFc3UlgTazOcPbH8dKdpRy45U/8eeKPafL5IKbLsor7fbQlwTF8+OqLkb 89y9GF2eQVAtBiz0WiHKoNOR0jVrz6GEoQZu1QaeaqhW3wZnMDs2ZIZkiTCQQBWU Pi9Z6TZDMY9yMy6SFyzvrso1u72OD5Dr8NJkGyZv7cIxTYoeb16g4b23/VHC5CTc 3+0E89qyEURXd01kXoUxXI6VzeLM/w== =t5D3 -----END PGP SIGNATURE----- --=-rgItgkzTV0zO7tkNlmZO--