linux/tools/perf
Frederic Weisbecker f413cdb80c perf_counter: Fix/complete ftrace event records sampling
This patch implements the kernel side support for ftrace event
record sampling.

A new counter sampling attribute is added:

   PERF_SAMPLE_TP_RECORD

which requests ftrace events record sampling. In this case
if a PERF_TYPE_TRACEPOINT counter is active and a tracepoint
fires, we emit the tracepoint binary record to the
perfcounter event buffer, as a sample.

Result, after setting PERF_SAMPLE_TP_RECORD attribute from perf
record:

 perf record -f -F 1 -a -e workqueue:workqueue_execution
 perf report -D

 0x21e18 [0x48]: event: 9
 .
 . ... raw event: size 72 bytes
 .  0000:  09 00 00 00 01 00 48 00 d0 c7 00 81 ff ff ff ff  ......H........
 .  0010:  0a 00 00 00 0a 00 00 00 21 00 00 00 00 00 00 00  ........!......
 .  0020:  2b 00 01 02 0a 00 00 00 0a 00 00 00 65 76 65 6e  +...........eve
 .  0030:  74 73 2f 31 00 00 00 00 00 00 00 00 0a 00 00 00  ts/1...........
 .  0040:  e0 b1 31 81 ff ff ff ff                          .......
.
0x21e18 [0x48]: PERF_EVENT_SAMPLE (IP, 1): 10: 0xffffffff8100c7d0 period: 33

The raw ftrace binary record starts at offset 0020.

Translation:

 struct trace_entry {
	type		= 0x2b = 43;
	flags		= 1;
	preempt_count	= 2;
	pid		= 0xa = 10;
	tgid		= 0xa = 10;
 }

 thread_comm = "events/1"
 thread_pid  = 0xa = 10;
 func	    = 0xffffffff8131b1e0 = flush_to_ldisc()

What will come next?

 - Userspace support ('perf trace'), 'flight data recorder' mode
   for perf trace, etc.

 - The unconditional copy from the profiling callback brings
   some costs however if someone wants no such sampling to
   occur, and needs to be fixed in the future. For that we need
   to have an instant access to the perf counter attribute.
   This is a matter of a flag to add in the struct ftrace_event.

 - Take care of the events recursivity! Don't ever try to record
   a lock event for example, it seems some locking is used in
   the profiling fast path and lead to a tracing recursivity.
   That will be fixed using raw spinlock or recursivity
   protection.

 - [...]

 - Profit! :-)

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Gabriel Munteanu <eduard.munteanu@linux360.ro>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-08-09 12:53:48 +02:00
..
Documentation perf report: Add missing command line options to man page 2009-08-05 16:09:28 +02:00
util perf symbol: Fix symbol parsing in certain cases: use the build-id as a symlink 2009-08-06 20:24:37 +02:00
.gitignore
CREDITS perf_counter tools: Add CREDITS file for Git contributors 2009-06-24 19:54:29 +02:00
Makefile perf: Auto-detect libelf 2009-08-06 20:25:13 +02:00
builtin-annotate.c perf_counter: PERF_SAMPLE_ID and inherited counters 2009-07-22 18:05:56 +02:00
builtin-help.c perf_counter tools: Add more warnings and fix/annotate them 2009-07-01 12:49:48 +02:00
builtin-list.c perf_counter tools: Add more warnings and fix/annotate them 2009-07-01 12:49:48 +02:00
builtin-record.c perf_counter: Fix/complete ftrace event records sampling 2009-08-09 12:53:48 +02:00
builtin-report.c perf report: Make --sort comm,dso,symbol the default 2009-08-05 13:16:04 +02:00
builtin-stat.c perf_counter: Improve perf stat and perf record option parsing 2009-07-22 18:05:56 +02:00
builtin-top.c perf top: Add mwait_idle_with_hints to skip_symbols[] 2009-08-02 13:58:16 +02:00
builtin.h
command-list.txt
design.txt perf_counter: Start documenting HAVE_PERF_COUNTERS requirements 2009-06-12 19:37:30 +02:00
perf.c perf_counter: Detect debugfs location 2009-07-22 18:05:57 +02:00
perf.h Merge branch 'perf-counters-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/peterz/linux-2.6-perf 2009-07-22 11:41:56 -07:00