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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D9F55C433F5 for ; Fri, 24 Sep 2021 23:12:03 +0000 (UTC) Received: from smtp2.osuosl.org (smtp2.osuosl.org [140.211.166.133]) (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 760D56125F for ; Fri, 24 Sep 2021 23:12:03 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 760D56125F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by smtp2.osuosl.org (Postfix) with ESMTP id 3233C4010F; Fri, 24 Sep 2021 23:12:03 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp2.osuosl.org ([127.0.0.1]) by localhost (smtp2.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id ianr_cvYwZjb; Fri, 24 Sep 2021 23:12:02 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [IPv6:2605:bc80:3010:104::8cd3:938]) by smtp2.osuosl.org (Postfix) with ESMTPS id C81884012F; Fri, 24 Sep 2021 23:12:01 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 9BF49C000F; Fri, 24 Sep 2021 23:12:01 +0000 (UTC) Received: from smtp3.osuosl.org (smtp3.osuosl.org [IPv6:2605:bc80:3010::136]) by lists.linuxfoundation.org (Postfix) with ESMTP id BBC54C000D for ; Fri, 24 Sep 2021 23:11:59 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp3.osuosl.org (Postfix) with ESMTP id AA37360768 for ; Fri, 24 Sep 2021 23:11:59 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp3.osuosl.org ([127.0.0.1]) by localhost (smtp3.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 0hbYashl85TQ for ; Fri, 24 Sep 2021 23:11:59 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.8.0 Received: from mga11.intel.com (mga11.intel.com [192.55.52.93]) by smtp3.osuosl.org (Postfix) with ESMTPS id 285C360761 for ; Fri, 24 Sep 2021 23:11:59 +0000 (UTC) X-IronPort-AV: E=McAfee;i="6200,9189,10117"; a="220987239" X-IronPort-AV: E=Sophos;i="5.85,321,1624345200"; d="scan'208";a="220987239" Received: from fmsmga002.fm.intel.com ([10.253.24.26]) by fmsmga102.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 Sep 2021 16:11:58 -0700 X-IronPort-AV: E=Sophos;i="5.85,321,1624345200"; d="scan'208";a="559859753" Received: from agluck-desk2.sc.intel.com (HELO agluck-desk2.amr.corp.intel.com) ([10.3.52.146]) by fmsmga002-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 Sep 2021 16:11:58 -0700 Date: Fri, 24 Sep 2021 16:11:57 -0700 From: "Luck, Tony" To: Andy Lutomirski Subject: Re: [PATCH 5/8] x86/mmu: Add mm-based PASID refcounting Message-ID: References: <20210920192349.2602141-1-fenghua.yu@intel.com> <20210920192349.2602141-6-fenghua.yu@intel.com> <87y27nfjel.ffs@tglx> <87o88jfajo.ffs@tglx> <87k0j6dsdn.ffs@tglx> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: Cc: Fenghua Yu , Dave Jiang , Raj Ashok , "Shankar, Ravi V" , "Peter Zijlstra \(Intel\)" , the arch/x86 maintainers , Linux Kernel Mailing List , Dave Hansen , iommu@lists.linux-foundation.org, Ingo Molnar , Borislav Petkov , Jacob Jun Pan , Josh Poimboeuf , Thomas Gleixner X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" On Fri, Sep 24, 2021 at 04:03:53PM -0700, Andy Lutomirski wrote: > 1. The context switch code needs to resync PASID. Unfortunately, this adds some overhead to every context switch, although a static_branch could minimize it for non-PASID users. Any solution that adds to context switch time isn't going to meet the definition of "perfect" either. -Tony _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu