From: Dave Hansen <dave.hansen@intel.com>
To: Feng Tang <feng.tang@intel.com>, Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
"H . Peter Anvin" <hpa@zytor.com>,
x86@kernel.org, linux-kernel@vger.kernel.org,
rui.zhang@intel.com, tim.c.chen@intel.com,
Xiongfeng Wang <wangxiongfeng2@huawei.com>,
Yu Liao <liaoyu15@huawei.com>
Subject: Re: [PATCH] x86/tsc: Extend the watchdog check exemption to 4S/8S machine
Date: Mon, 10 Oct 2022 07:23:10 -0700 [thread overview]
Message-ID: <aff10f33-b379-6872-f180-b38f6a0a669a@intel.com> (raw)
In-Reply-To: <Y0N0ENurfliW315D@feng-clx>
On 10/9/22 18:23, Feng Tang wrote:
>>> diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
>>> index cafacb2e58cc..b4ea79cb1d1a 100644
>>> --- a/arch/x86/kernel/tsc.c
>>> +++ b/arch/x86/kernel/tsc.c
>>> @@ -1217,7 +1217,7 @@ static void __init check_system_tsc_reliable(void)
>>> if (boot_cpu_has(X86_FEATURE_CONSTANT_TSC) &&
>>> boot_cpu_has(X86_FEATURE_NONSTOP_TSC) &&
>>> boot_cpu_has(X86_FEATURE_TSC_ADJUST) &&
>>> - nr_online_nodes <= 2)
>>> + nr_online_nodes <= 8)
>> So you're saying all 8 socket systems since Broadwell (?) are TSC
>> sync'ed ?
> No, I didn't mean that. I haven't got chance to any 8 sockets
> machine, and I got a report last month that on one 8S machine,
> the TSC was judged 'unstable' by HPET as watchdog.
That's not a great check. Think about numa=fake=4U, for instance. Or a
single-socket system with persistent memory and high bandwidth memory.
Basically 'nr_online_nodes' is a software construct. It's going to be
really hard to infer anything from it about what the _hardware_ is.
next prev parent reply other threads:[~2022-10-10 14:23 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-09 5:12 Feng Tang
2022-10-09 13:01 ` Peter Zijlstra
2022-10-10 1:23 ` Feng Tang
2022-10-10 14:23 ` Dave Hansen [this message]
2022-10-11 1:09 ` Feng Tang
2022-10-11 7:51 ` Feng Tang
2022-10-11 13:01 ` Peter Zijlstra
2022-10-12 8:44 ` Feng Tang
2022-10-11 7:52 ` Peter Zijlstra
2022-10-11 13:33 ` Zhang Rui
2022-10-11 14:01 ` Peter Zijlstra
2022-10-11 14:11 ` Feng Tang
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