linux-kernel - Re: [PATCHSET 00/17] perf tools: Introduce new 'ftrace' command (v4)

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Message-ID: <20130828145708.GA20153@jeder.rdu.redhat.com>
Date:	Wed, 28 Aug 2013 10:57:08 -0400
From:	Jeremy Eder <jeder@...hat.com>
To:	Namhyung Kim <namhyung@...nel.org>
Cc:	Jiri Olsa <jolsa@...hat.com>,
	Arnaldo Carvalho de Melo <acme@...stprotocols.net>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Paul Mackerras <paulus@...ba.org>,
	Ingo Molnar <mingo@...nel.org>,
	Namhyung Kim <namhyung.kim@....com>,
	LKML <linux-kernel@...r.kernel.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	David Ahern <dsahern@...il.com>,
	Stephane Eranian <eranian@...gle.com>,
	Jeremy Eder <jeder@...hat.com>
Subject: Re: [PATCHSET 00/17] perf tools: Introduce new 'ftrace' command (v4)

On 130813 11:20:52, Namhyung Kim wrote:
> ------------8<-------------
> diff --git a/tools/perf/builtin-ftrace.c b/tools/perf/builtin-ftrace.c
> index 9e78ec19caeb..10590b794cae 100644
> --- a/tools/perf/builtin-ftrace.c
> +++ b/tools/perf/builtin-ftrace.c
> @@ -555,17 +555,25 @@ sleep:
>  	while (true) {
>  		int n = read(trace_fd, buf, sizeof(buf));
>  
> -		if (n < 0)
> -			goto out_close;
> -		if (n == 0)
> +		if (n < 0) {
> +			if (errno == EINTR || errno == EAGAIN)
> +				break;
> +			perror("flush read");
> +			goto out_close2;
> +		} else if (n == 0)
>  			break;
> -		if (write(output_fd, buf, n) != n)
> -			goto out_close;
> +
> +		if (write(output_fd, buf, n) != n) {
> +			perror("flush write");
> +			goto out_close2;
> +		}
>  
>  		byte_written += n;
>  	}
>  	fra->state = RECORD_STATE__DONE;
>  
> +out_close2:
> +	close(output_fd);
>  out_close:
>  	close(trace_fd);
>  out:
> @@ -579,6 +587,8 @@ out:
>  		pthread_cond_signal(&recorder_ready_cond);
>  		pthread_mutex_unlock(&recorder_mutex);
>  	}
> +
> +	pr_debug2("done with %ld bytes\n", (long)byte_written);
>  	return fra;
>  }
>  

Hmm, I already had hunk #3 in your git tree v4.

> @@ -1139,12 +1149,12 @@ retry:
>  		return record;
>  	}
>  
> -	munmap(fra->map, pevent_get_page_size(ftrace->pevent));
> -	fra->map = NULL;
> -
>  	if (fra->done)
>  		return NULL;
>  
> +	munmap(fra->map, pevent_get_page_size(ftrace->pevent));
> +	fra->map = NULL;
> +
>  	fra->offset += pevent_get_page_size(ftrace->pevent);
>  	if (fra->offset >= fra->size) {
>  		/* EOF */


After patching your tree with just the first 2 hunks, I'm able to
get ftrace-style function graphing out of perf.

# ./perf ftrace record df
Filesystem           1K-blocks     Used Available Use% Mounted on
<snip>...

# ./perf --no-pager ftrace show | head -20
overriding event (11) ftrace:funcgraph_entry with new print handler
overriding event (10) ftrace:funcgraph_exit with new print handler
  2)   0.686 us |  finish_task_switch();
  2)   0.260 us |  finish_wait();
  2)            |  mutex_lock() {
  2)   0.211 us |    _cond_resched();
  2)   1.170 us |  }
  2)   0.319 us |  generic_pipe_buf_confirm();
  2)   0.261 us |  generic_pipe_buf_map();
  2)   0.129 us |  generic_pipe_buf_unmap();
  2)   0.747 us |  anon_pipe_buf_release();
  2)   0.138 us |  mutex_unlock();
  2)            |  __wake_up_sync_key() {
  2)   0.279 us |    _raw_spin_lock_irqsave();
  2)   0.135 us |    __wake_up_common();
  2)   0.133 us |    __lock_text_start();
  2)   3.386 us |  }
  2)            |  kill_fasync() {
  2)            |  smp_reschedule_interrupt() {
  2)   0.130 us |    kvm_guest_apic_eoi_write();

Nice.

Not sure if you intend to move all ftrace functionality over to
perf ftrace, but the function graph timings is a great start and something sorely
missing.

Do you intend to add -e event support or -l function-specific options ?  In the real
world, without filtering on events or functions, I've had systems hang, plus
performance impact is too great.

A common invocation of ftrace via trace-cmd is:
# trace-cmd record -p function_graph -e irq:* -l do_IRQ ping -c1 www.redhat.com

So possible perf equivalent?
# ./perf ftrace record -e irq:* -e do_IRQ ping -c1 www.redhat.com

Thanks!
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