linux-kernel - Re: [PATCH V6 15/17] perf tools: Intel BTS to always update thread stack trace number

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Date:	Fri, 19 Jun 2015 13:11:18 -0300
From:	Arnaldo Carvalho de Melo <acme@...nel.org>
To:	Adrian Hunter <adrian.hunter@...el.com>
Cc:	Ingo Molnar <mingo@...nel.org>, linux-kernel@...r.kernel.org,
	Jiri Olsa <jolsa@...hat.com>
Subject: Re: [PATCH V6 15/17] perf tools: Intel BTS to always update thread
 stack trace number

Em Fri, May 29, 2015 at 04:33:43PM +0300, Adrian Hunter escreveu:
> The enhanced thread stack is used by higher layers but still requires
> the trace number.  The trace number is used to distinguish discontinuous
> sections of trace (for example from Snapshot mode or Sample mode), which
> cause the thread stack to be flushed.
> 
> Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
> ---
>  tools/perf/util/intel-bts.c | 18 ++++++++++++++----
>  1 file changed, 14 insertions(+), 4 deletions(-)
> 
> diff --git a/tools/perf/util/intel-bts.c b/tools/perf/util/intel-bts.c
> index b068860..cd7bde3 100644
> --- a/tools/perf/util/intel-bts.c
> +++ b/tools/perf/util/intel-bts.c
> @@ -27,6 +27,8 @@
>  #include "machine.h"
>  #include "session.h"
>  #include "util.h"
> +#include "thread.h"
> +#include "thread-stack.h"
>  #include "debug.h"
>  #include "tsc.h"
>  #include "auxtrace.h"
> @@ -443,19 +445,22 @@ static int intel_bts_process_buffer(struct intel_bts_queue *btsq,
>  
>  static int intel_bts_process_queue(struct intel_bts_queue *btsq, u64 *timestamp)
>  {
> -	struct auxtrace_buffer *buffer = btsq->buffer;
> +	struct auxtrace_buffer *buffer = btsq->buffer, *old_buffer = buffer;
>  	struct auxtrace_queue *queue;
> +	struct thread *thread;
>  	int err;
>  
>  	if (btsq->done)
>  		return 1;
>  
>  	if (btsq->pid == -1) {
> -		struct thread *thread;
> -
> -		thread = machine__find_thread(btsq->bts->machine, -1, btsq->tid);
> +		thread = machine__find_thread(btsq->bts->machine, -1,
> +					      btsq->tid);
>  		if (thread)
>  			btsq->pid = thread->pid_;
> +	} else {
> +		thread = machine__findnew_thread(btsq->bts->machine, btsq->pid,
> +						 btsq->tid);

Humm, so what will be done with the reference count you got from
machine__findnew_thread()? You have to drop it when you're done with
using this thread.

>  	}
>  
>  	queue = &btsq->bts->queues.queue_array[btsq->queue_nr];
> @@ -485,6 +490,11 @@ static int intel_bts_process_queue(struct intel_bts_queue *btsq, u64 *timestamp)
>  	    intel_bts_do_fix_overlap(queue, buffer))
>  		return -ENOMEM;
>  
> +	if (!btsq->bts->synth_opts.callchain && thread &&
> +	    (!old_buffer || btsq->bts->sampling_mode ||
> +	     (btsq->bts->snapshot_mode && !buffer->consecutive)))
> +		thread_stack__set_trace_nr(thread, buffer->buffer_nr + 1);
> +
>  	err = intel_bts_process_buffer(btsq, buffer);
>  
>  	auxtrace_buffer__drop_data(buffer);
> -- 
> 1.9.1
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