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 231E4C352A1 for ; Wed, 30 Nov 2022 05:50:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233666AbiK3Fuc (ORCPT ); Wed, 30 Nov 2022 00:50:32 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50716 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233660AbiK3Fu2 (ORCPT ); Wed, 30 Nov 2022 00:50:28 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 36D0159FEE for ; Tue, 29 Nov 2022 21:50:27 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id C2115B81A31 for ; Wed, 30 Nov 2022 05:50:25 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 75056C433B5; Wed, 30 Nov 2022 05:50:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1669787424; bh=mB2f49/57pI4KkyvYIzhm6qW9AM1dpfnpwL8vxECIZ8=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:From; b=ckT3e9A4tGqG/uSE4R4x0FXmTXCyTrqmOrRbULLg6mB0m7tMkKzXmH4xd/zWr7uMO t/+B+orTwGvC5dyTbFm7mlB4TCE3/E2M90dVg+vWtl0vQQoFfwUavKPlU3GGzQSS7V C75xDIBK6sonNRPzW16zY84J6xJxR5NVum0HCkeiuOFlCAU6hNWmzreTIKdjBaFCvU 3N7LaGrMowgTdDAEnAMkpXZpAPj17jPsZvU+smLTkmUW59xEyz95F2/5dfRVSde9oF TkfsYAREGocJt3Vc+R+Br2NDjpVmLYmSbkiAUyQorQfpH+8yuTmKbi2cLaRzXOP9En aaMGdsThVUFtQ== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id 1C1885C097E; Tue, 29 Nov 2022 21:50:24 -0800 (PST) Date: Tue, 29 Nov 2022 21:50:24 -0800 From: "Paul E. McKenney" To: Feng Tang Cc: Thomas Gleixner , linux-kernel@vger.kernel.org, john.stultz@linaro.org, sboyd@kernel.org, corbet@lwn.net, Mark.Rutland@arm.com, maz@kernel.org, kernel-team@meta.com, neeraju@codeaurora.org, ak@linux.intel.com, zhengjun.xing@intel.com, Chris Mason , John Stultz , Waiman Long Subject: Re: [PATCH clocksource 1/3] clocksource: Reject bogus watchdog clocksource measurements Message-ID: <20221130055024.GM4001@paulmck-ThinkPad-P17-Gen-1> Reply-To: paulmck@kernel.org References: <20221122220712.GP4001@paulmck-ThinkPad-P17-Gen-1> <20221123212348.GI4001@paulmck-ThinkPad-P17-Gen-1> <20221129192915.GD4001@paulmck-ThinkPad-P17-Gen-1> <20221130041206.GK4001@paulmck-ThinkPad-P17-Gen-1> <20221130051600.GL4001@paulmck-ThinkPad-P17-Gen-1> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Nov 30, 2022 at 01:35:08PM +0800, Feng Tang wrote: > On Tue, Nov 29, 2022 at 09:16:00PM -0800, Paul E. McKenney wrote: > > On Wed, Nov 30, 2022 at 12:49:24PM +0800, Feng Tang wrote: > > > On Tue, Nov 29, 2022 at 08:12:06PM -0800, Paul E. McKenney wrote: > > > > On Wed, Nov 30, 2022 at 09:38:00AM +0800, Feng Tang wrote: > > > > > On Tue, Nov 29, 2022 at 11:29:15AM -0800, Paul E. McKenney wrote: > > > > > [...] > > > > > > > > > IIUC, this will make TSC to watchdog HPET every 500 ms. We have got > > > > > > > > > report that the 500ms watchdog timer had big impact on some parallel > > > > > > > > > workload on big servers, that was another factor for us to seek > > > > > > > > > stopping the timer. > > > > > > > > > > > > > > > > Another approach would be to slow it down. Given the tighter bounds > > > > > > > > on skew, it could be done every (say) 10 seconds while allowing > > > > > > > > 2 milliseconds skew instead of the current 100 microseconds. > > > > > > > > > > > > > > Yes, this can reduce the OS noise much. One problem is if we make it > > > > > > > a general interface, there is some clocksource whose warp time is > > > > > > > less than 10 seconds, like ACPI PM_TIMER (3-4 seconds), and I don't > > > > > > > know if other ARCHs have similar cases. > > > > > > > > > > > > Maybe a simpler approach is for systems with such high sensitivity to > > > > > > OS noise to simply disable the clocksource watchdog. ;-) > > > > > > > > > > That's what the reported did, test with and without "tsc=reliable" > > > > > parameter :) > > > > > > > > > > And AFAIK, many customers with big server farms hate to add more > > > > > cmdline parameters when we suggested so. > > > > > > > > It can be surprisingly hard. It is sometimes easier to patch the kernel > > > > to change the default. > > > > > > Indeed, sometimes we were askd to provide patch than cmdline parameters :) > > > > Do any of them like CONFIG_BOOT_CONFIG_EMBED? ;-) > > > > > > Part of the problem is getting the right set > > > > of command-line parameters associated with the right versions of the > > > > kernel in the not-uncommon case where different portions of the server > > > > farm are running different versions of the kernel. > > > > > > > > > > > > > Is this about the concern of possible TSC frequency calibration > > > > > > > > > issue, as the 40 ms per second drift between HPET and TSC? With > > > > > > > > > b50db7095fe0 backported, we also have another patch to force TSC > > > > > > > > > calibration for those platforms which get the TSC freq directly > > > > > > > > > from CPUID or MSR and don't have such info in dmesg: > > > > > > > > > "tsc: Refined TSC clocksource calibration: 2693.509 MHz" > > > > > > > > > > > > > > > > > > https://lore.kernel.org/lkml/20220509144110.9242-1-feng.tang@intel.com/ > > > > > > > > > > > > > > > > > > We did met tsc calibration issue due to some firmware issue, and > > > > > > > > > this can help to catch it. You can try it if you think it's relevant. > > > > > > > > > > > > > > > > I am giving this a go, thank you! > > > > > > > > > > > > > > Thanks for spending time testing it! > > > > > > > > > > > > And here are the results from setting tsc_force_recalibrate to 1: > > > > > > > > > > > > $ dmesg | grep -E 'calibrat|clocksource' > > > > > > [    5.272939] clocksource: refined-jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 1910969940391419 ns > > > > > > [   16.830644] clocksource: hpet: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 76450417870 ns > > > > > > [   17.938020] clocksource: tsc-early: mask: 0xffffffffffffffff max_cycles: 0x36a8d32ce31, max_idle_ns: 881590731004 ns > > > > > > [   24.548583] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 1911260446275000 ns > > > > > > [   49.762432] clocksource: Switched to clocksource tsc-early > > > > > > [   50.076769] clocksource: acpi_pm: mask: 0xffffff max_cycles: 0xffffff, max_idle_ns: 2085701024 ns > > > > > > [   55.615946] clocksource: tsc: mask: 0xffffffffffffffff max_cycles: 0x36a8d32ce31, max_idle_ns: 881590731004 ns > > > > > > [   55.640270] clocksource: Switched to clocksource tsc > > > > > > [   56.694371] tsc: Warning: TSC freq calibrated by CPUID/MSR differs from what is calibrated by HW timer, please check with vendor!! > > > > > > [   56.724550] tsc: Previous calibrated TSC freq:        1896.000 MHz > > > > > > [   56.737646] tsc: TSC freq recalibrated by [HPET]:     1975.000 MHz > > > > > > > > > > Looks like there is really something wrong here. I assume the first > > > > > number '1896 MHz' is got from CPUID(0x15)'s math calculation. > > > > > > > > How about this from earlier in that same console? > > > > > > > > [ 0.000000] efi: EFI v2.80 by American Megatrends > > > > [ 0.000000] efi: ACPI=0x6f569000 ACPI 2.0=0x6f569014 TPMFinalLog=0x6f56b000 SMBIOS=0x753e1000 SMBIOS 3.0=0x753e0000 MEMATTR=0x62176018 ESRT=0x64bd1018 TPMEventLog=0x58737018 > > > > [ 0.000000] [Firmware Bug]: TPM Final Events table missing or invalid > > > > [ 0.000000] SMBIOS 3.5.0 present. > > > > [ 0.000000] DMI: Quanta Grand Teton 1F0TUBZ0007/Grand Teton MB, BIOS F0T_1A15 08/25/2022 > > > > [ 0.000000] tsc: Detected 1900.000 MHz processor > > > > [ 0.000000] tsc: Detected 1896.000 MHz TSC > > > > > > I'm still not sure, but it's likely from CPUID(0x15). I met cases > > > that even severs of same generations get their tsc frequence from > > > different sources. > > > > > > I locally have debug patch to check it: > > > > > > diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c > > > index cafacb2e58cc..82ddb4b0529a 100644 > > > --- a/arch/x86/kernel/tsc.c > > > +++ b/arch/x86/kernel/tsc.c > > > @@ -654,8 +654,11 @@ unsigned long native_calibrate_tsc(void) > > > * frequency and is the most accurate one so far we have. This > > > * is considered a known frequency. > > > */ > > > - if (crystal_khz != 0) > > > + if (crystal_khz != 0) { > > > + printk("tsc: using CPUID[0x15] crystal_khz= %d kHz ebx=%d eax=%d\n", > > > + crystal_khz, ebx_numerator, eax_denominator); > > > setup_force_cpu_cap(X86_FEATURE_TSC_KNOWN_FREQ); > > > + } > > > > > > /* > > > * Some Intel SoCs like Skylake and Kabylake don't report the crystal > > > @@ -668,6 +671,7 @@ unsigned long native_calibrate_tsc(void) > > > cpuid(0x16, &eax_base_mhz, &ebx, &ecx, &edx); > > > crystal_khz = eax_base_mhz * 1000 * > > > eax_denominator / ebx_numerator; > > > + printk("tsc: using CPUID[0x16] base_khz=%d kHz\n", crystal_khz); > > > } > > > > > > if (crystal_khz == 0) > > > > I will give this one a go, thank you! > > > > > This remind me that maybe we can add a line in dmesg telling people > > > which exact soure that the TSC frequency comes from (CPUID, MSR or > > > calibration from HW timers like HPET/PM_TIMER). > > > > Thus far, it seems that this information could be useful. > > > > > > > I thinks 2 more things could be try: > > > > > > > > > > * add "nohpet" to the cmdline, so the tsc_force_recalibrate should use > > > > > ACPI PM_TIMER to do the calibration, say a third-party check. > > > > > > > > OK, getting things teed up for TSC recalibration and nohpet. > > > > > > > > > * If the system don't have auto-adjusted time setting like NTP, I > > > > > guess the system time will have obvious drift comparing to a normal > > > > > clock or a mobile phone time, as the deviation is about 4%, which > > > > > is 2.4 minutes per hour. > > > > > > > > No ntpd, but there is a chronyd. > > > > > > > > I will let you know what happens with HPET disabled and TSC recalibration > > > > enabled. > > > > And here you go: > > > > [    0.000000] tsc: Detected 1900.000 MHz processor > > [    0.000000] tsc: Detected 1896.000 MHz TSC > > [    5.254788] clocksource: refined-jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 1910969940391419 ns > > [   25.669260] clocksource: tsc-early: mask: 0xffffffffffffffff max_cycles: 0x36a8d32ce31, max_idle_ns: 881590731004 ns > > [   32.182958] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 1911260446275000 ns > > [   57.785756] clocksource: Switched to clocksource tsc-early > > [   58.106661] clocksource: acpi_pm: mask: 0xffffff max_cycles: 0xffffff, max_idle_ns: 2085701024 ns > > [   63.578433] clocksource: tsc: mask: 0xffffffffffffffff max_cycles: 0x36a8d32ce31, max_idle_ns: 881590731004 ns > > [   63.602169] clocksource: Switched to clocksource tsc > > [   64.636612] tsc: Warning: TSC freq calibrated by CPUID/MSR differs from what is calibrated by HW timer, please check with vendor!! > > [   64.664615] tsc: Previous calibrated TSC freq:        1896.000 MHz > > [   64.677714] tsc: TSC freq recalibrated by [PM_TIMER]:         1975.000 MHz > > Great! As both HPET and PM_TIMER get the same calibration 1975.000 MHz, > and it matches the 40ms drift per second you mentioned earlier, this > seems like the CPUID(0x15) gave the wrong frequence number. > > Or unlikely, HPET and PM_TIMER are driven by the same circuit source, > which has deviation. > > Either way, I think the HW/FW could have some problem. And this time with your printk()s: [    0.000000] tsc: using CPUID[0x15] crystal_khz= 24000 kHz ebx=158 eax=2 [    0.000000] tsc: Detected 1900.000 MHz processor [    0.000000] tsc: Detected 1896.000 MHz TSC [    5.268858] clocksource: refined-jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 1910969940391419 ns [   25.706231] clocksource: tsc-early: mask: 0xffffffffffffffff max_cycles: 0x36a8d32ce31, max_idle_ns: 881590731004 ns [   32.223011] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 1911260446275000 ns [   57.823933] clocksource: Switched to clocksource tsc-early [   58.144840] clocksource: acpi_pm: mask: 0xffffff max_cycles: 0xffffff, max_idle_ns: 2085701024 ns [   63.613713] clocksource: tsc: mask: 0xffffffffffffffff max_cycles: 0x36a8d32ce31, max_idle_ns: 881590731004 ns [   63.637323] clocksource: Switched to clocksource tsc [   64.673579] tsc: Warning: TSC freq calibrated by CPUID/MSR differs from what is calibrated by HW timer, please check with vendor!! [   64.703719] tsc: Previous calibrated TSC freq:        1896.000 MHz [   64.716816] tsc: TSC freq recalibrated by [PM_TIMER]:         1974.999 MHz What would be good next steps to check up on the hardware and firmware? (My next step involves a pillow, but will follow up tomorrow morning Pacific Time.) Thanx, Paul