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=-2.3 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 7E445C433FF for ; Mon, 29 Jul 2019 17:32:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5E0D9206DD for ; Mon, 29 Jul 2019 17:32:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728970AbfG2Rcp (ORCPT ); Mon, 29 Jul 2019 13:32:45 -0400 Received: from mail-wm1-f53.google.com ([209.85.128.53]:53921 "EHLO mail-wm1-f53.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726709AbfG2Rco (ORCPT ); Mon, 29 Jul 2019 13:32:44 -0400 Received: by mail-wm1-f53.google.com with SMTP id x15so54624212wmj.3 for ; Mon, 29 Jul 2019 10:32:43 -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=7HtRXlu8gLMjmdEPvaN8cA83YotUWNPBua50ykhl1as=; b=A65QqXNSZ3dJ5JF+Vht/NnUrKphnY607BTQmX0zceoxAcXp7QhBKz/DV7QTst3ytVx /H4u46pUlGqB6CFcuQIE7ITlMgSwddPu7hwoXufb/tBgg1nz3CoLTCaAMivyKh+fERZ+ MGBpjOr0FFSzmd/8ctBO+RUgAOaChMeKtnG7tkRkJdcid0YhyDjUHfK9+8XKoFbGGPwp hgxaJ4gUGT5bF1xoH4aPADNbnY+d/SCm4AWfQzi1spTa8mqn458dkge0QnD+h95dH563 lL26ZI4xyH25Jj598CRtWpP6GYsnOz1ivYNu8aRV3AzB+FflWlgRO3UtrotMz66brcfZ tDrA== X-Gm-Message-State: APjAAAXKGgXLKYFp5cBKK+3bqzXFkhCibjdKqDlcIfLA9t2dp8MMeZWE wbkplg5BQ8uDVWSPrRcn0AfmaA== X-Google-Smtp-Source: APXvYqyQa3kYTSQWS/BcXsNm1KJQXcbT9e4AFH5fZzlj6Rb0limYVCm41jejT/v1Mtw2we7gPPNGyA== X-Received: by 2002:a1c:b707:: with SMTP id h7mr98962564wmf.45.1564421562548; Mon, 29 Jul 2019 10:32:42 -0700 (PDT) Received: from [192.168.10.150] ([93.56.166.5]) by smtp.gmail.com with ESMTPSA id b8sm79772886wmh.46.2019.07.29.10.32.40 (version=TLS1_3 cipher=AEAD-AES128-GCM-SHA256 bits=128/128); Mon, 29 Jul 2019 10:32:41 -0700 (PDT) Subject: Re: [patch 11/12] hrtimer: Prepare support for PREEMPT_RT To: Steven Rostedt , Juergen Gross Cc: Thomas Gleixner , LKML , x86@kernel.org, Sebastian Siewior , Anna-Maria Gleixner , Arnaldo Carvalho de Melo , Jiri Olsa References: <20190726183048.982726647@linutronix.de> <20190726185753.737767218@linutronix.de> <42299f02-ff29-f7e3-45f0-b9fef041aec9@suse.com> <20190729110806.57c57399@gandalf.local.home> From: Paolo Bonzini Openpgp: preference=signencrypt Message-ID: <9a9bde89-e0b3-a7b9-749e-a6b35d74b729@redhat.com> Date: Mon, 29 Jul 2019 19:30:33 +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: <20190729110806.57c57399@gandalf.local.home> 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 29/07/19 17:08, Steven Rostedt wrote: > On Sun, 28 Jul 2019 11:06:50 +0200 > Juergen Gross wrote: > >> In case we'd want to change that I'd rather not special case timers, but >> apply a more general solution to the quite large amount of similar >> cases: I assume the majority of cpu_relax() uses are affected, so adding >> a paravirt op cpu_relax() might be appropriate. >> >> That could be put under CONFIG_PARAVIRT_SPINLOCK. If called in a guest >> it could ask the hypervisor to give up the physical cpu voluntarily >> (in Xen this would be a "yield" hypercall). > > Seems paravirt wants our cpu_chill() ;-) Actually that is not really a joke! :) Paolo