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Date:   Wed, 20 Jun 2018 11:15:32 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Thomas Gleixner <tglx@linutronix.de>
Cc:     Pavel Tatashin <pasha.tatashin@oracle.com>,
        steven.sistare@oracle.com, daniel.m.jordan@oracle.com,
        linux@armlinux.org.uk, schwidefsky@de.ibm.com,
        heiko.carstens@de.ibm.com, john.stultz@linaro.org,
        sboyd@codeaurora.org, x86@kernel.org, linux-kernel@vger.kernel.org,
        mingo@redhat.com, hpa@zytor.com, douly.fnst@cn.fujitsu.com,
        prarit@redhat.com, feng.tang@intel.com, pmladek@suse.com,
        gnomes@lxorguk.ukuu.org.uk
Subject: Re: [PATCH v10 7/7] x86/tsc: use tsc early
Message-ID: <20180620091532.GK2476@hirez.programming.kicks-ass.net>
References: <20180615174204.30581-1-pasha.tatashin@oracle.com>
 <20180615174204.30581-8-pasha.tatashin@oracle.com>
 <alpine.DEB.2.21.1806192335390.10546@nanos.tec.linutronix.de>
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On Wed, Jun 20, 2018 at 01:52:10AM +0200, Thomas Gleixner wrote:
>  u64 native_sched_clock(void)
>  {
> +	if (static_branch_likely(&__use_tsc))
> +		return cycles_2_ns(rdtsc());
>  
> +	if (static_branch_unlikely(&tsc_early_enabled)) {
> +		if (tsc_early_sched_clock)
> +			return cycles_2_ns(rdtsc());
>  	}

I'm still puzzled by the entire need for tsc_early_enabled and all that.
Esp. since both branches do the exact same thing:

	return cycles_2_ns(rdtsc());