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From:   Pavel Tatashin <pasha.tatashin@oracle.com>
Date:   Thu, 19 Jul 2018 14:38:09 -0400
Message-ID: <CAGM2rebBN0v0epfTssM=ShiWZ4GTDaN_cgGWdKE4+k+jV6CxyA@mail.gmail.com>
Subject: Re: [PATCH v14 20/25] x86/tsc: calibrate tsc only once
To:     tglx@linutronix.de
Cc:     peterz@infradead.org, Steven Sistare <steven.sistare@oracle.com>,
        Daniel Jordan <daniel.m.jordan@oracle.com>,
        linux@armlinux.org.uk, schwidefsky@de.ibm.com,
        Heiko Carstens <heiko.carstens@de.ibm.com>,
        John Stultz <john.stultz@linaro.org>, sboyd@codeaurora.org,
        x86@kernel.org, LKML <linux-kernel@vger.kernel.org>,
        mingo@redhat.com, hpa@zytor.com, douly.fnst@cn.fujitsu.com,
        prarit@redhat.com, feng.tang@intel.com,
        Petr Mladek <pmladek@suse.com>, gnomes@lxorguk.ukuu.org.uk,
        linux-s390@vger.kernel.org, boris.ostrovsky@oracle.com,
        jgross@suse.com, pbonzini@redhat.com
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On Thu, Jul 19, 2018 at 12:49 PM Pavel Tatashin
<pasha.tatashin@oracle.com> wrote:
>
> > So create two functions. native_...early..() and native....(). The early
> > one does not contain the hpet/pmtimer stuff and it replaces the ops.pointer
> > with the late one which contains all of it.
>
> Good idea. Actually, the late one will contain only hpet/pmtimer and I
> will set it only if tsc frequency was not determined only.

If we determined tsc early in boot using one of the quick methods:
from cpuid/msr/quick_pit, can we assume that frequencies of all other
CPUs will be determined the same way? Or do we still have to fallback
to PIT/HPET/PMTIMER? I wondering if we support heterogeneous
multi-socket platforms with different CPUs, because that the only
platforms where I see such scenario is possible.

Thank you,
Pavel