linux-kernel - Re: [PATCH 24/41] perf tools: Add cpu to struct thread

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Message-ID: <53C56BB0.7000805@intel.com>
Date:	Tue, 15 Jul 2014 20:58:08 +0300
From:	Adrian Hunter <adrian.hunter@...el.com>
To:	Arnaldo Carvalho de Melo <acme@...nel.org>
CC:	Peter Zijlstra <peterz@...radead.org>,
	linux-kernel@...r.kernel.org, David Ahern <dsahern@...il.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Jiri Olsa <jolsa@...hat.com>,
	Namhyung Kim <namhyung@...il.com>,
	Paul Mackerras <paulus@...ba.org>,
	Stephane Eranian <eranian@...gle.com>
Subject: Re: [PATCH 24/41] perf tools: Add cpu to struct thread

On 15/07/2014 5:24 p.m., Arnaldo Carvalho de Melo wrote:
> Em Mon, Jul 14, 2014 at 01:02:48PM +0300, Adrian Hunter escreveu:
>> Tools may wish to track on which cpu a thread
>> is running.  Add 'cpu' to struct thread for
>> that purpose.
>>
>> This will be used to determine the cpu when
>> decoding a per-thread Instruction Trace.
>
> Humm, is this the last cpu we got some event telling the cpu was running
> on? Continuing looking at the patches...

Yes.  Intel PT decoding uses sched_switch events to determine which
task is running on which cpu.  The Intel PT data comes straight
from the hardware which doesn't know about linux threads.

>
> - Arnaldo
>
>> Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
>> ---
>>   tools/perf/util/thread.c | 1 +
>>   tools/perf/util/thread.h | 1 +
>>   2 files changed, 2 insertions(+)
>>
>> diff --git a/tools/perf/util/thread.c b/tools/perf/util/thread.c
>> index b9a3ee4..2f8c0c1 100644
>> --- a/tools/perf/util/thread.c
>> +++ b/tools/perf/util/thread.c
>> @@ -69,6 +69,7 @@ struct thread *thread__new(pid_t pid, pid_t tid)
>>   		thread->pid_ = pid;
>>   		thread->tid = tid;
>>   		thread->ppid = -1;
>> +		thread->cpu = -1;
>>   		INIT_LIST_HEAD(&thread->comm_list);
>>
>>   		comm_str = malloc(32);
>> diff --git a/tools/perf/util/thread.h b/tools/perf/util/thread.h
>> index b4269af..e4920ff 100644
>> --- a/tools/perf/util/thread.h
>> +++ b/tools/perf/util/thread.h
>> @@ -17,6 +17,7 @@ struct thread {
>>   	pid_t			pid_; /* Not all tools update this */
>>   	pid_t			tid;
>>   	pid_t			ppid;
>> +	int			cpu;
>>   	char			shortname[3];
>>   	bool			comm_set;
>>   	bool			dead; /* if set thread has exited */
>> --
>> 1.8.3.2
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