From: Fei Li <fei1.li@intel.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: <linux-kernel@vger.kernel.org>, <x86@kernel.org>,
<dave.hansen@intel.com>, <gregkh@linuxfoundation.org>,
<tglx@linutronix.de>, <mingo@redhat.com>, <bp@alien8.de>,
<dave.hansen@linux.intel.com>, <hpa@zytor.com>,
<Yu1.Wang@intel.com>, <conghui.chen@intel.com>,
<fengwei.yin@intel.com>
Subject: Re: [PATCH] x86/acrn: Set X86_FEATURE_TSC_KNOWN_FREQ
Date: Wed, 26 Oct 2022 11:32:27 +0800 [thread overview]
Message-ID: <Y1iqS3FuCjPE8icm@louislifei-OptiPlex-7090> (raw)
In-Reply-To: <Y1fjMnX9UOVo2+K5@hirez.programming.kicks-ass.net>
On 2022-10-25 at 15:22:58 +0200, Peter Zijlstra wrote:
> On Tue, Oct 25, 2022 at 04:41:47PM +0800, Fei Li wrote:
> > Avoiding recalibration by setting X86_FEATURE_TSC_KNOWN_FREQ.
> > This patch also removes `inline` for acrn_get_tsc_khz() since
> > it doesn't make sense.
>
Hi Peter
Thanks for your comments.
> Can we have a few words on how this is supposed to work at all?
If the TSC frequency is known from the acrn_get_tsc_khz(),
the TSC frequency does not need to be recalibrated.
We can avoid recalibration by setting X86_FEATURE_TSC_KNOWN_FREQ.
>
> Supposedly the HV is providing host rate through this ACRN CPUID leaf?
ACRN would provide the calibrated TSC frequency, not just the
host rate through this CPUID leaf.
> How does it deal with systems where TSC isn't known stable?
>
prev parent reply other threads:[~2022-10-26 3:28 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-25 8:41 [PATCH] x86/acrn: Set X86_FEATURE_TSC_KNOWN_FREQ Fei Li
2022-10-25 13:22 ` Peter Zijlstra
2022-10-26 3:32 ` Fei Li [this message]
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=Y1iqS3FuCjPE8icm@louislifei-OptiPlex-7090 \
--to=fei1.li@intel.com \
--cc=Yu1.Wang@intel.com \
--cc=bp@alien8.de \
--cc=conghui.chen@intel.com \
--cc=dave.hansen@intel.com \
--cc=dave.hansen@linux.intel.com \
--cc=fengwei.yin@intel.com \
--cc=gregkh@linuxfoundation.org \
--cc=hpa@zytor.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=peterz@infradead.org \
--cc=tglx@linutronix.de \
--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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.