From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758259AbcFAOwj (ORCPT ); Wed, 1 Jun 2016 10:52:39 -0400 Received: from mx1.redhat.com ([209.132.183.28]:43170 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752901AbcFAOwi (ORCPT ); Wed, 1 Jun 2016 10:52:38 -0400 Message-ID: <1464792754.16365.104.camel@redhat.com> Subject: Re: [PATCH 1/2] x86/entry: Avoid interrupt flag save and restore From: Rik van Riel To: Paolo Bonzini , linux-kernel@vger.kernel.org, x86@kernel.org Cc: Andy Lutomirski , Peter Zijlstra , "H. Peter Anvin" , Ingo Molnar , Thomas Gleixner Date: Wed, 01 Jun 2016 10:52:34 -0400 In-Reply-To: <1464611414-12379-2-git-send-email-pbonzini@redhat.com> References: <1464611414-12379-1-git-send-email-pbonzini@redhat.com> <1464611414-12379-2-git-send-email-pbonzini@redhat.com> Content-Type: multipart/signed; micalg="pgp-sha256"; protocol="application/pgp-signature"; boundary="=-QDXxwyxsDpE1dzo5U+Og" Mime-Version: 1.0 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.31]); Wed, 01 Jun 2016 14:52:38 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --=-QDXxwyxsDpE1dzo5U+Og Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Mon, 2016-05-30 at 14:30 +0200, Paolo Bonzini wrote: > Thanks to all the work that was done by Andy Lutomirski and others, > enter_from_user_mode and prepare_exit_to_usermode are now called only > with > interrupts disabled.=C2=A0=C2=A0Let's provide them a version of > user_enter/user_exit > that skips saving and restoring the interrupt flag. >=20 > On an AMD-based machine I tested this patch on, with force-enabled > context tracking, the speed-up in system calls was 90 clock cycles or > 6%, > measured with the following simple benchmark: >=20 Reviewed-by: Rik van Riel --=20 All Rights Reversed. --=-QDXxwyxsDpE1dzo5U+Og Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQEcBAABCAAGBQJXTvayAAoJEM553pKExN6DBVkH/A4bztNygFD9LfT8BVpRMTg7 47VJ2Rf2KfXL304CIVbtdu53SH3eKvjo4Kx0Y8xgHhL8St3EmXxeV2OiZvzO2yRY qvam5+Vm34vtwNVdwCINXCZa2DaTAP3SNRz6JTkXXP3AXLSrPE6BJb6j9ifakTPG tcmEzEQ6wGpGahbBuEtsD/1D8THolzCQe0r6YfTRvFyIKQX+esymjHnmYNanT96D CcfnUy8n9IFKW16+l4E8benu6+GozoFxLyYUZ9d/iKFRw8j9xYzeflPnhR2yJZxs RmlrXi17+ccgAZu8ADUn32JkM5r8Jgzva6760BWOrtx1mlbytiMX6Q7JsLoIgSA= =lai0 -----END PGP SIGNATURE----- --=-QDXxwyxsDpE1dzo5U+Og--