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=-0.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 DFB48C43603 for ; Tue, 17 Dec 2019 20:44:07 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id ACCA52053B for ; Tue, 17 Dec 2019 20:44:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1576615447; bh=YED4RPfRYlt98bF0R98iY51ABN4X2dYsrsJd5BxgjPw=; h=References:In-Reply-To:From:Date:Subject:To:Cc:List-ID:From; b=EvNacbs1aKz+EsB6e5nCNank6xqGi+2R95/tl5jwU/35kYGW3QErPdCcF1Td49AXZ Qg5HMDjr4dq+MwVsCB6xeFxypHIbTW1m/NLDjVm+2lSZCYgxPmCFhSgEIARvEiiBEu 2fLg/i5q1B+ur/v9Jj6IGuvA6ytl8nlwcfFaMMvo= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728506AbfLQUoG (ORCPT ); Tue, 17 Dec 2019 15:44:06 -0500 Received: from mail-lj1-f196.google.com ([209.85.208.196]:43228 "EHLO mail-lj1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727905AbfLQUoG (ORCPT ); Tue, 17 Dec 2019 15:44:06 -0500 Received: by mail-lj1-f196.google.com with SMTP id a13so12462394ljm.10 for ; Tue, 17 Dec 2019 12:44:04 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux-foundation.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=2cf4f/QMuXkJeMkXz5zpiT8/Vid/X0vf07yHkg4bF34=; b=AiH6mnOw1/7BYh931DcV6Hdvt+DTFflY7cdUvCiSJPSv1jGSEGCxXohtV7+Ndw/fuS LK39OyGZBJvOBtZI32H4AROOrz4v5Iwx8JYmkW266IF3WT4lBy9qVzCGcKPqWT7Vgz1V eockp+SBbZ6O9i1DvC9E2d5sGe2PfxvehWel0= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=2cf4f/QMuXkJeMkXz5zpiT8/Vid/X0vf07yHkg4bF34=; b=DrVtNnKhtvF1uSUk5IRcKgTWFo4ZIQ7GrC4rA55URGWjWjdXBwyvC1B0/3Q2p49pwg LjlqrfzQU7mw4f5+pYgSttxsOBTR5jtj2HGA98ID1LqUun0anYbaNU+gxknTH0N1untz NMjS+SttE6+4bghdDMdPc8v5MAWja+4OaD3296+RuTAqmQR7CouIjArpV1udIS2AKlTZ Wvzagi7EbSCzPYIq9kXe+5pnkoLCvSVibMqyeKbLU4T6+jUmZ2/trm/9yhBEev76AuwX RLHyg2pth1Ykuxy4ttGPRUV/0MHk8y54+cSzEy5xIhgDqQFHFH5uxLilIJ3MsOdndwFF nczQ== X-Gm-Message-State: APjAAAW85WNFzFAut2KmPLXRnFSUGcUdKevLUqnsjNpF17rZIn6Zkw38 K43wTlS/25blHuuL1ZOWkGjBcjBs9UM= X-Google-Smtp-Source: APXvYqw3WnRIlCmg67xgkYmulpzi3iBkzx56zxDaCjwMlvID5TrFUFSjteZx3zLMHf6mcQHremqCRA== X-Received: by 2002:a2e:814e:: with SMTP id t14mr4554954ljg.149.1576615443378; Tue, 17 Dec 2019 12:44:03 -0800 (PST) Received: from mail-lj1-f179.google.com (mail-lj1-f179.google.com. [209.85.208.179]) by smtp.gmail.com with ESMTPSA id d24sm13114852lja.82.2019.12.17.12.44.02 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 17 Dec 2019 12:44:02 -0800 (PST) Received: by mail-lj1-f179.google.com with SMTP id r19so12493223ljg.3 for ; Tue, 17 Dec 2019 12:44:02 -0800 (PST) X-Received: by 2002:a2e:9ad1:: with SMTP id p17mr2567128ljj.26.1576615442111; Tue, 17 Dec 2019 12:44:02 -0800 (PST) MIME-Version: 1.0 References: <20191217115547.GA68104@gmail.com> <20191217193039.GF2844@hirez.programming.kicks-ass.net> <20191217203506.GI2844@hirez.programming.kicks-ass.net> In-Reply-To: <20191217203506.GI2844@hirez.programming.kicks-ass.net> From: Linus Torvalds Date: Tue, 17 Dec 2019 12:43:46 -0800 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [GIT PULL] timer fixes To: Peter Zijlstra Cc: Ingo Molnar , Linux Kernel Mailing List , Thomas Gleixner , Andrew Morton , Borislav Petkov Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Dec 17, 2019 at 12:35 PM Peter Zijlstra wrote: > > Pray.. the TSC MSR is still writable from SMM, so BIOS monkeys could > still do what they've been doing for decades. Sure. And the HPET is unreliable, so the checking causes issues. Which one should we worry about? > Also, what consititutes a 'modern' CPU? I think anything that has TSC_STABLE set should likely be considered more reliable than HPET. Or whatever the bit is called. The "doesn't stop in idle" thing. > > The HPET seems to get disabled on all the modern platforms, why do we > > even have it enabled by default? > > These new ones yeah, cuz they wrecked HPET in PC10 :/ That's my point. HPET isn't _used_ by Windows, so it gets no testing, so it will continue to have bugs. At least the TSC is used. I do agree about the whole SMM issue, but it seems less of a pain than the HPET issue. Linus