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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D716BC4332F for ; Mon, 30 Oct 2023 16:04:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233801AbjJ3QEi (ORCPT ); Mon, 30 Oct 2023 12:04:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56346 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233311AbjJ3QEg (ORCPT ); Mon, 30 Oct 2023 12:04:36 -0400 Received: from desiato.infradead.org (desiato.infradead.org [IPv6:2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 71BFDEA for ; Mon, 30 Oct 2023 09:04:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; 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; bh=uAoarrbeEOi+ThvFg0exUiGAqfLtD6t4DohDctCATSQ=; b=XAMxg6SONejIbZYDLjmqQ4e/RG pdA5o0RYfETlyIi0zD2FyhT1wqg8ORb/7jfgqGnqWqxkAhdJiNf6G2HUZcJCDHFh6XjKI3CpwCQus +jP12vFCGCARNiVZ+wVW6kEobPQRRxD1yB5TI+Gk64pH8hDt8GVZSrV1yc8k3jBtdgqNELYp5PV0o IMrSeBA96BpfFm81e08nssZQqsIuaHcpfHX+WK25zTNUnRA5UKi6OJvzckiN/cMhERIjpXJ7rfbwI dTSQMKoabdWHKri9W95IxD2hEGiHsftzqCc+rNc1VjQBwjjBSGxccnvgOFZOlEfoTmOittasP3uHS rU40jwcA==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.96 #2 (Red Hat Linux)) id 1qxUkY-0042jG-1B; Mon, 30 Oct 2023 16:04:22 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 0E837300478; Mon, 30 Oct 2023 17:04:22 +0100 (CET) Date: Mon, 30 Oct 2023 17:04:22 +0100 From: Peter Zijlstra To: x86@kernel.org Cc: linux-kernel@vger.kernel.org, Thomas Gleixner , Arjan van de Ven , feng.tang@intel.com Subject: Re: [PATCH] x86/tsc: Have tsc=recalibrate override things Message-ID: <20231030160422.GB19106@noisy.programming.kicks-ass.net> References: <20231030160050.GA15024@noisy.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20231030160050.GA15024@noisy.programming.kicks-ass.net> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Oct 30, 2023 at 05:00:50PM +0100, Peter Zijlstra wrote: > --- > arch/x86/kernel/tsc.c | 26 +++++++++++++------------- > 1 file changed, 13 insertions(+), 13 deletions(-) > > diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c > index 15f97c0abc9d..ebca304ecea0 100644 > --- a/arch/x86/kernel/tsc.c > +++ b/arch/x86/kernel/tsc.c > @@ -1430,14 +1430,13 @@ static void tsc_refine_calibration_work(struct work_struct *work) > hpet ? "HPET" : "PM_TIMER", > (unsigned long)freq / 1000, > (unsigned long)freq % 1000); > + } else { > > - return; > + /* Make sure we're within 1% */ > + if (abs(tsc_khz - freq) > tsc_khz/100) > + goto out; > } > > - /* Make sure we're within 1% */ > - if (abs(tsc_khz - freq) > tsc_khz/100) > - goto out; > - > tsc_khz = freq; > pr_info("Refined TSC clocksource calibration: %lu.%03lu MHz\n", > (unsigned long)tsc_khz / 1000, > @@ -1475,18 +1474,19 @@ static int __init init_tsc_clocksource(void) > if (boot_cpu_has(X86_FEATURE_NONSTOP_TSC_S3)) > clocksource_tsc.flags |= CLOCK_SOURCE_SUSPEND_NONSTOP; > > - /* > - * When TSC frequency is known (retrieved via MSR or CPUID), we skip > - * the refined calibration and directly register it as a clocksource. > - */ > if (boot_cpu_has(X86_FEATURE_TSC_KNOWN_FREQ)) { > if (boot_cpu_has(X86_FEATURE_ART)) > art_related_clocksource = &clocksource_tsc; > - clocksource_register_khz(&clocksource_tsc, tsc_khz); > - clocksource_unregister(&clocksource_tsc_early); > > - if (!tsc_force_recalibrate) > - return 0; > + /* > + * When TSC frequency is known (retrieved via MSR or CPUID), we > + * skip the refined calibration and directly register it as a > + * clocksource. > + */ > + if (!tsc_force_recalibrate) { > + clocksource_register_khz(&clocksource_tsc, tsc_khz); > + clocksource_unregister(&clocksource_tsc_early); + return 0; Clearly I should step away from the keyboard now. > + } > } > > schedule_delayed_work(&tsc_irqwork, 0); >