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Commit bcc84ec6 authored by Stephane Eranian's avatar Stephane Eranian Committed by Arnaldo Carvalho de Melo
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perf record: Add ability to name registers to record 



This patch modifies the -I/--int-regs option to enablepassing the name
of the registers to sample on interrupt. Registers can be specified by
their symbolic names. For instance on x86, --intr-regs=ax,si.

The motivation is to reduce the size of the perf.data file and the
overhead of sampling by only collecting the registers useful to a
specific analysis. For instance, for value profiling, sampling only the
registers used to passed arguements to functions.

With no parameter, the --intr-regs still records all possible registers
based on the architecture.

To name registers, it is necessary to use the long form of the option,
i.e., --intr-regs:

  $ perf record --intr-regs=si,di,r8,r9 .....

To record any possible registers:

  $ perf record -I .....
  $ perf report --intr-regs ...

To display the register, one can use perf report -D

To list the available registers:

  $ perf record --intr-regs=\?
  available registers: AX BX CX DX SI DI BP SP IP FLAGS CS SS R8 R9 R10 R11 R12 R13 R14 R15

Signed-off-by: default avatarStephane Eranian <eranian@google.com>
Tested-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kan Liang <kan.liang@intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1441039273-16260-4-git-send-email-eranian@google.com


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent c5e991ee

tools/perf/Documentation/perf-record.txt

+5 −1
Original line number Diff line number Diff line
@@ -276,7 +276,11 @@ filter out the startup phase of the program, which is often very different. 
--intr-regs::

Capture machine state (registers) at interrupt, i.e., on counter overflows for

each sample. List of captured registers depends on the architecture. This option

is off by default.

is off by default. It is possible to select the registers to sample using their

symbolic names, e.g. on x86, ax, si. To list the available registers use

--intr-regs=\?. To name registers, pass a comma separated list such as

--intr-regs=ax,bx. The list of register is architecture dependent.





--running-time::

Record running and enabled time for read events (:S)

tools/perf/builtin-record.c

+5 −2
Original line number Diff line number Diff line
@@ -27,8 +27,10 @@ 
#include "util/cpumap.h"

#include "util/thread_map.h"

#include "util/data.h"

#include "util/perf_regs.h"

#include "util/auxtrace.h"

#include "util/parse-branch-options.h"

#include "util/parse-regs-options.h"



#include <unistd.h>

#include <sched.h>
@@ -1080,8 +1082,9 @@ struct option __record_options[] = { 
		    "sample transaction flags (special events only)"),

	OPT_BOOLEAN(0, "per-thread", &record.opts.target.per_thread,

		    "use per-thread mmaps"),

	OPT_BOOLEAN('I', "intr-regs", &record.opts.sample_intr_regs,

		    "Sample machine registers on interrupt"),

	OPT_CALLBACK_OPTARG('I', "intr-regs", &record.opts.sample_intr_regs, NULL, "any register",

		    "sample selected machine registers on interrupt,"

		    " use -I ? to list register names", parse_regs),

	OPT_BOOLEAN(0, "running-time", &record.opts.running_time,

		    "Record running/enabled time of read (:S) events"),

	OPT_CALLBACK('k', "clockid", &record.opts,

tools/perf/perf.h

+1 −1
Original line number Diff line number Diff line
@@ -54,7 +54,6 @@ struct record_opts { 
	bool	     sample_time_set;

	bool	     callgraph_set;

	bool	     period;

	bool	     sample_intr_regs;

	bool	     running_time;

	bool	     full_auxtrace;

	bool	     auxtrace_snapshot_mode;
@@ -64,6 +63,7 @@ struct record_opts { 
	unsigned int auxtrace_mmap_pages;

	unsigned int user_freq;

	u64          branch_stack;

	u64	     sample_intr_regs;

	u64	     default_interval;

	u64	     user_interval;

	size_t	     auxtrace_snapshot_size;

tools/perf/util/Build

+1 −0
Original line number Diff line number Diff line
@@ -83,6 +83,7 @@ libperf-$(CONFIG_AUXTRACE) += intel-pt-decoder/ 
libperf-$(CONFIG_AUXTRACE) += intel-pt.o

libperf-$(CONFIG_AUXTRACE) += intel-bts.o

libperf-y += parse-branch-options.o

libperf-y += parse-regs-options.o



libperf-$(CONFIG_LIBELF) += symbol-elf.o

libperf-$(CONFIG_LIBELF) += probe-file.o

tools/perf/util/evsel.c

+1 −1
Original line number Diff line number Diff line
@@ -787,7 +787,7 @@ void perf_evsel__config(struct perf_evsel *evsel, struct record_opts *opts) 
		perf_evsel__config_callgraph(evsel, opts, &callchain_param);



	if (opts->sample_intr_regs) {

		attr->sample_regs_intr = PERF_REGS_MASK;

		attr->sample_regs_intr = opts->sample_intr_regs;

		perf_evsel__set_sample_bit(evsel, REGS_INTR);

	}