linux-kernel - Re: [PATCH 1/3] perf/x86/intel/pt: Add new timing packet enables

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Message-ID: <87vbd1kgde.fsf@ashishki-desk.ger.corp.intel.com>
Date:	Thu, 30 Jul 2015 14:57:17 +0300
From:	Alexander Shishkin <alexander.shishkin@...ux.intel.com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Ingo Molnar <mingo@...hat.com>, linux-kernel@...r.kernel.org,
	adrian.hunter@...el.com, x86@...nel.org, hpa@...or.com,
	acme@...radead.org
Subject: Re: [PATCH 1/3] perf/x86/intel/pt: Add new timing packet enables

Peter Zijlstra <peterz@...radead.org> writes:

> On Fri, Jul 17, 2015 at 04:34:08PM +0300, Alexander Shishkin wrote:
>> +#define PT_CONFIG_MASK (RTIT_CTL_TSC_EN     |	\
>> +			RTIT_CTL_DISRETC    |	\
>> +			RTIT_CTL_CYCLEACC   |	\
>> +			RTIT_CTL_MTC_EN     |	\
>> +			RTIT_CTL_MTC_RANGE  |	\
>> +			RTIT_CTL_CYC_THRESH |   \
>> +			RTIT_CTL_PSB_FREQ)
>>  
>
> #define RTIT_CTL_CYC (RTIT_CTL_CYCLEACC   | \
> 		      RTIT_CTL_CYC_THRESH | \
> 		      RTIT_CTL_PSB_FREQ)

PSB_FREQ is not, strictly speaking, related to cycle accurate mode. Both
adjustable psb frequency and cycle accurate mode settings are enumerated
with the same CPUID bit, but they really do different things unrelated
to one another.

>> +	if (config & (RTIT_CTL_MTC_EN | RTIT_CTL_MTC_RANGE)) {
>
> 	if (config & RTIT_CTL_MTC) {
>
> Would that make sense?

To me either way is fine. Want me to respin it?

Regards,
--
Alex
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