Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:18 as permitted sender) client-ip=2620:137:e000::1:18;
Message-ID: <57bdc43e-4753-66f8-b54b-860be3239026@intel.com>
Date:   Fri, 4 Mar 2022 14:41:16 +0200
MIME-Version: 1.0
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101
 Firefox/91.0 Thunderbird/91.5.0
Subject: Re: [PATCH V2 02/11] perf/x86: Add support for TSC as a perf event
 clock
Content-Language: en-US
To:     Peter Zijlstra <peterz@infradead.org>
Cc:     Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Jiri Olsa <jolsa@redhat.com>, linux-kernel@vger.kernel.org,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
        Dave Hansen <dave.hansen@linux.intel.com>, x86@kernel.org,
        kvm@vger.kernel.org, H Peter Anvin <hpa@zytor.com>,
        Mathieu Poirier <mathieu.poirier@linaro.org>,
        Suzuki K Poulose <suzuki.poulose@arm.com>,
        Leo Yan <leo.yan@linaro.org>
References: <20220214110914.268126-1-adrian.hunter@intel.com>
 <20220214110914.268126-3-adrian.hunter@intel.com>
 <YiIHJAfqY0XKsmya@hirez.programming.kicks-ass.net>
From:   Adrian Hunter <adrian.hunter@intel.com>
Organization: Intel Finland Oy, Registered Address: PL 281, 00181 Helsinki,
 Business Identity Code: 0357606 - 4, Domiciled in Helsinki
In-Reply-To: <YiIHJAfqY0XKsmya@hirez.programming.kicks-ass.net>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 7bit
Precedence: bulk

On 04/03/2022 14:33, Peter Zijlstra wrote:
> On Mon, Feb 14, 2022 at 01:09:05PM +0200, Adrian Hunter wrote:
>> +u64 perf_hw_clock(void)
>> +{
>> +	return rdtsc_ordered();
>> +}
> 
> Why the _ordered ?

To be on the safe-side - in case it matters.  trace_clock_x86_tsc() also uses the ordered variant.