From: Peter Zijlstra <peterz@infradead.org>
To: Prarit Bhargava <prarit@redhat.com>
Cc: linux-kernel@vger.kernel.org,
Patrick Geary <patrickg@supermicro.com>,
Jonathan Corbet <corbet@lwn.net>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
"H. Peter Anvin" <hpa@zytor.com>,
x86@kernel.org,
Mauro Carvalho Chehab <mchehab+samsung@kernel.org>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
Pawan Gupta <pawan.kumar.gupta@linux.intel.com>,
Juergen Gross <jgross@suse.com>,
"Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
Viresh Kumar <viresh.kumar@linaro.org>,
Daniel Drake <drake@endlessm.com>,
Michael Zhivich <mzhivich@akamai.com>,
linux-doc@vger.kernel.org
Subject: Re: [PATCH] x86/tsc: Add kernel options to disable CPUID and MSR calibrations
Date: Wed, 26 Feb 2020 17:54:07 +0100 [thread overview]
Message-ID: <20200226165407.GB18400@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20200226164308.14468-1-prarit@redhat.com>
On Wed, Feb 26, 2020 at 11:43:08AM -0500, Prarit Bhargava wrote:
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index dbc22d684627..0316aadfff08 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -4942,7 +4942,7 @@
> See Documentation/admin-guide/mm/transhuge.rst
> for more details.
>
> - tsc= Disable clocksource stability checks for TSC.
> + tsc=option[,option...] Various TSC options.
> Format: <string>
> [x86] reliable: mark tsc clocksource as reliable, this
> disables clocksource verification at runtime, as well
> @@ -4960,6 +4960,12 @@
> in situations with strict latency requirements (where
> interruptions from clocksource watchdog are not
> acceptable).
> + [x86] no_cpuid_calibration: Disable the CPUID TSC
> + calibration. Used in situations where the CPUID
> + TSC khz does not match the actual CPU TSC khz
> + [x86] no_msr_calibration: Disable the MSR TSC
> + calibration. Used in situations where the MSR
> + TSC khz does not match the actual CPU TSC khz.
Do we want to mention that these situations are mostly broken firmware?
Also do mention that if you disable these you might not boot due to not
having a PIT/HPET at all?
As it stands, I find this text a little too encouraging.
> tsx= [X86] Control Transactional Synchronization
> Extensions (TSX) feature in Intel processors that
next prev parent reply other threads:[~2020-02-26 16:54 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-26 16:43 [PATCH] x86/tsc: Add kernel options to disable CPUID and MSR calibrations Prarit Bhargava
2020-02-26 16:54 ` Peter Zijlstra [this message]
2020-02-26 23:27 ` Thomas Gleixner
2020-02-27 12:58 ` Prarit Bhargava
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200226165407.GB18400@hirez.programming.kicks-ass.net \
--to=peterz@infradead.org \
--cc=akpm@linux-foundation.org \
--cc=bp@alien8.de \
--cc=corbet@lwn.net \
--cc=drake@endlessm.com \
--cc=hpa@zytor.com \
--cc=jgross@suse.com \
--cc=jpoimboe@redhat.com \
--cc=linux-doc@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mchehab+samsung@kernel.org \
--cc=mingo@redhat.com \
--cc=mzhivich@akamai.com \
--cc=patrickg@supermicro.com \
--cc=pawan.kumar.gupta@linux.intel.com \
--cc=prarit@redhat.com \
--cc=rafael.j.wysocki@intel.com \
--cc=tglx@linutronix.de \
--cc=viresh.kumar@linaro.org \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox