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Message-ID: <52A9C4BF.4050206@intel.com>
Date: Thu, 12 Dec 2013 16:14:23 +0200
From: Adrian Hunter <adrian.hunter@intel.com>
Organization: Intel Finland Oy, Registered Address: PL 281, 00181 Helsinki,
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To: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
CC: Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Peter Zijlstra <a.p.zijlstra@chello.nl>,
        Ingo Molnar <mingo@redhat.com>, linux-kernel@vger.kernel.org,
        David Ahern <dsahern@gmail.com>,
        Frederic Weisbecker <fweisbec@gmail.com>, Jiri Olsa <jolsa@redhat.com>,
        Mike Galbraith <efault@gmx.de>, Namhyung Kim <namhyung@gmail.com>,
        Paul Mackerras <paulus@samba.org>,
        Stephane Eranian <eranian@google.com>, Andi Kleen <ak@linux.intel.com>
Subject: Re: [PATCH v0 14/71] perf tools: Add cpu to struct thread
References: <1386765443-26966-1-git-send-email-alexander.shishkin@linux.intel.com> <1386765443-26966-15-git-send-email-alexander.shishkin@linux.intel.com> <20131211141908.GC1458@ghostprotocols.net>
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On 11/12/13 16:19, Arnaldo Carvalho de Melo wrote:
> Em Wed, Dec 11, 2013 at 02:36:26PM +0200, Alexander Shishkin escreveu:
>> From: Adrian Hunter <adrian.hunter@intel.com>
>>
>> Tools may wish to track on which cpu a thread
>> is running.  Add 'cpu' to struct thread for
>> that purpose.  Also add machine functions to
>> get / set the cpu for a tid.
>>
>> This will be used to determine the cpu when
>> decoding a per-thread Instruction Trace.
>>
>>
>> +++ b/tools/perf/util/machine.c
>> @@ -1412,3 +1412,29 @@ pid_t machine__get_thread_pid(struct machine *machine, pid_t tid)
>>  
>>  	return thread->pid_;
>>  }
>> +
>> +int machine__get_thread_cpu(struct machine *machine, pid_t tid, pid_t *pid)
>> +{
>> +	struct thread *thread = machine__find_thread(machine, tid);
>> +
>> +	if (!thread)
>> +		return -1;
>> +
>> +	if (pid)
>> +		*pid = thread->pid_;
>> +
>> +	return thread->cpu;
>> +}
> 
> What is the problem with:
> 
> 	struct thread *thread = machine__find_thread(machine, tid);
> 	pid_t pid = thread->pid_;
> 	int cpu = thread->cpu;
> 
> In your case you'll have:
> 
> 	int pid;
> 	int cpu = machine__get_thread_cpu(machine, tid, &pid);
> 
> Which is slightly more compact, but then we end up with a function that
> from its name should just get a 'cpu' but also asks for the pid.
> 
> I think it is better to just use what we have (machine__find_thread),
> have a 'thread' variable and then use any of its members, directly.

OK