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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 A0049C432C1 for ; Wed, 25 Sep 2019 07:50:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7C86A20872 for ; Wed, 25 Sep 2019 07:50:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2442609AbfIYHum (ORCPT ); Wed, 25 Sep 2019 03:50:42 -0400 Received: from mx1.redhat.com ([209.132.183.28]:49282 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2437273AbfIYHum (ORCPT ); Wed, 25 Sep 2019 03:50:42 -0400 Received: from mail-wm1-f72.google.com (mail-wm1-f72.google.com [209.85.128.72]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 0AC59882F2 for ; Wed, 25 Sep 2019 07:50:42 +0000 (UTC) Received: by mail-wm1-f72.google.com with SMTP id s25so1506960wmh.1 for ; Wed, 25 Sep 2019 00:50:41 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:openpgp:message-id :date:user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=HYW+7OIc+oWfT/yx6/DrRQ9OVDX/Tk7EiyaM2Cojmhs=; b=KkRQ9AETJ1cfOUjDVxuQUHZXflR9CnNAn3kyC+CKgZuC330Zzjr7PqAtzlmoYZcwuE OfjZSii7h4wH0ZR3k//qLA6SFAhrTd99eVJpmEAryI3ag7usmeow5fpcquXv462Q1e7H CEKMe2UKcswEsw4Js4ed3P27VQi/pjyfrIgsdW2uDj8bsC9Dd488PvezZdJR6pcU8+i9 NZcDZTAzVgp/wpopfawdmaTkwC30PznRh3o40NYw/GZagaUhoGBhm/EDcy8K68XW5Fez zuLj8eJYzAxhFp2uk+J66sRxZM+g+yv0QgJTZri8FtiaL86wGx8n9ZlRy1UEr0KxTaQ4 Kgog== X-Gm-Message-State: APjAAAWrEm8q2Mv9rLEDeO7EZ/bA/wHn5AQ2YASzhHFi9GDlEhEzq1vq 6MKWVnKpXDL/wQ6TrN2lTKStTODjmfLX4VZfCOjvxxpJodyK+0HeGDJT+rBMB/u6YJJcxeGPKXp VvdpmFghprDkGtPwAcRGlalvI X-Received: by 2002:a7b:c258:: with SMTP id b24mr5872499wmj.21.1569397840502; Wed, 25 Sep 2019 00:50:40 -0700 (PDT) X-Google-Smtp-Source: APXvYqxtvZMsWmeH3/rg+4pkIrLnbZniZnoLTRybC7fHAMsikPSeeBEnuwwdmtqFzu/RZt1IlIru4Q== X-Received: by 2002:a7b:c258:: with SMTP id b24mr5872474wmj.21.1569397840246; Wed, 25 Sep 2019 00:50:40 -0700 (PDT) Received: from ?IPv6:2001:b07:6468:f312:9520:22e6:6416:5c36? ([2001:b07:6468:f312:9520:22e6:6416:5c36]) by smtp.gmail.com with ESMTPSA id b15sm3904376wmb.28.2019.09.25.00.50.39 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 25 Sep 2019 00:50:39 -0700 (PDT) Subject: Re: [PATCH 15/17] KVM: retpolines: x86: eliminate retpoline from vmx.c exit handlers To: Andrea Arcangeli Cc: Vitaly Kuznetsov , "Dr. David Alan Gilbert" , Marcelo Tosatti , Peter Xu , kvm@vger.kernel.org, linux-kernel@vger.kernel.org References: <20190920212509.2578-1-aarcange@redhat.com> <20190920212509.2578-16-aarcange@redhat.com> <87o8zb8ik1.fsf@vitty.brq.redhat.com> <7329012d-0b3b-ce86-f58d-3d2d5dc5a790@redhat.com> <20190923190514.GB19996@redhat.com> <20190924214657.GE4658@redhat.com> From: Paolo Bonzini Openpgp: preference=signencrypt Message-ID: <5e047696-c641-da4b-1215-ebecbb492417@redhat.com> Date: Wed, 25 Sep 2019 09:50:38 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20190924214657.GE4658@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 24/09/19 23:46, Andrea Arcangeli wrote: >>> >>> I would keep only EXIT_REASON_MSR_WRITE, EXIT_REASON_PREEMPTION_TIMER, >>> EXIT_REASON_EPT_MISCONFIG and add EXIT_REASON_IO_INSTRUCTION. >> Intuition doesn't work great when it comes to CPU speculative >> execution runtime. I can however run additional benchmarks to verify >> your theory that keeping around frequent retpolines will still perform >> ok. > On one most recent CPU model there's no measurable difference with > your list or my list with a hrtimer workload (no cpuid). It's > challenging to measure any difference below 0.5%. Let's keep the short list then. Paolo