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=-0.6 required=3.0 tests=DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,T_DKIM_INVALID autolearn=ham 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 4A6E7C5CFC1 for ; Tue, 19 Jun 2018 18:49:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0877220661 for ; Tue, 19 Jun 2018 18:49:37 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="btwVvfHu" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0877220661 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030578AbeFSStf (ORCPT ); Tue, 19 Jun 2018 14:49:35 -0400 Received: from merlin.infradead.org ([205.233.59.134]:56138 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030283AbeFSStc (ORCPT ); Tue, 19 Jun 2018 14:49:32 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=Ny60tXFFGW56tzPrk9E9VM+3xmwqemMW88ML5zYwPjw=; b=btwVvfHuU0YKqDWDbHHsZ1z4z N3OkyG/RN9Pjg+sTta+wSHrY+8nVvzMqIqK0BYlsLs/1lms1+luHd1Ln61xVRaeelqSDWd+E+4ohH pCr+bxeYC9loJb/0xtNVA7QyE72syc8iTNEzSUXCBFJB7GatpAOv/JfoQNdoBh1uMKMhX49075L2c QlS4JJzpvbQFbJBjERc9J5vw/JoUqFU4iY+w+iWYOE3bL3T7IwUJ2PaIUoGOVlygKzvnPEnb6vPi9 XQ1S8y/dzPHLV8U19XSWmB5T1LzA1u6RLIcOHufiUisEuXFU6sMj1iUBLzOMq1haQn4FuutuVVCvn vMGrlSz7w==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1fVLeZ-0007Aq-Rh; Tue, 19 Jun 2018 18:46:56 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 6AAA02026ACCD; Tue, 19 Jun 2018 20:46:54 +0200 (CEST) Date: Tue, 19 Jun 2018 20:46:54 +0200 From: Peter Zijlstra To: Thomas Gleixner Cc: Pavel Tatashin , steven.sistare@oracle.com, daniel.m.jordan@oracle.com, linux@armlinux.org.uk, schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, john.stultz@linaro.org, sboyd@codeaurora.org, x86@kernel.org, linux-kernel@vger.kernel.org, mingo@redhat.com, hpa@zytor.com, douly.fnst@cn.fujitsu.com, prarit@redhat.com, feng.tang@intel.com, pmladek@suse.com, gnomes@lxorguk.ukuu.org.uk Subject: Re: [PATCH v10 1/7] x86/tsc: remove tsc_disabled flag Message-ID: <20180619184654.GG2494@hirez.programming.kicks-ass.net> References: <20180615174204.30581-1-pasha.tatashin@oracle.com> <20180615174204.30581-2-pasha.tatashin@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.0 (2018-05-17) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jun 19, 2018 at 07:32:49PM +0200, Thomas Gleixner wrote: > On Fri, 15 Jun 2018, Pavel Tatashin wrote: > > > tsc_disabled is set when notsc is passed as kernel parameter. The reason we > > have notsc is to avoid timing problems on multi-socket systems. We already > > have a mechanism, however, to detect and resolve these issues by invoking > > tsc unstable path. Thus, make notsc to behave the same as tsc=unstable. > > notsc also excludes TSC from being used at all It does not; there is TSC usage even if you boot with notsc on. See how it does not clear X86_FEATURE_TSC for instance.