From: Peter Zijlstra <peterz@infradead.org>
To: Peng Hao <peng.hao2@zte.com.cn>
Cc: tglx@linutronix.de, pbonzini@redhat.com, mingo@redhat.com,
x86@kernel.org, len.brown@intel.com,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] x86: tsc: fix L2 guest always in tsc_early clocksource
Date: Mon, 23 Apr 2018 21:37:23 +0200 [thread overview]
Message-ID: <20180423193723.GO4082@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <1524532134-31408-1-git-send-email-peng.hao2@zte.com.cn>
On Tue, Apr 24, 2018 at 09:08:54AM +0800, Peng Hao wrote:
> In L2 guest tsc_read_refs always return ULLONG_MAX, and that will
> call tsc_refine_calibration_work periodly. So L2 guest will read
> acpi timer port 0x608 periodly.
> The patch will let it out of "if(tsc_start == -1){}" infinite loop.
Help me out a little. What's an L2 guest?
And I'm assuming you don't have HPET and then end up wanting to use
PM-timer? Which is also busted and resturns crap results?
So if the whole TSC sync has no way of ever working; what is your patch
doing? How is the actual TSC calibrated?
Should you instead be using fast_calibrate() and passing in a known
value from the host? Thereby avoiding all this calibration nonsense
entirely.
prev parent reply other threads:[~2018-04-23 19:37 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-24 1:08 Peng Hao
2018-04-23 19:37 ` Peter Zijlstra [this message]
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