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Message-ID: <CABPqkBT1R_SJiQkjujS4dN5yQZPakjOmmCLNR3DmNxTmVT_p9A@mail.gmail.com>
Date: Fri, 24 Feb 2012 16:28:33 +0100
From: Stephane Eranian <eranian@...gle.com>
To: David Ahern <dsahern@...il.com>
Cc: linux-kernel@...r.kernel.org, acme@...hat.com,
peterz@...radead.org, mingo@...e.hu, ravitillo@....gov,
khandual@...ux.vnet.ibm.com, asharma@...com,
robert.richter@....com, ming.m.lin@...el.com,
vweaver1@...s.utk.edu, andi@...stfloor.org
Subject: Re: [PATCH] perf report: auto-detect branch stack sampling mode
On Fri, Feb 24, 2012 at 4:24 PM, David Ahern <dsahern@...il.com> wrote:
> On 2/24/12 2:40 AM, Stephane Eranian wrote:
>>
>>
>> This patch adds auto-detection of samples with taken branch stacks.
>> The auto-detection avoids having to specify the -b or --branch-stack
>> option on the cmdline.
>>
>> The patch adds a new feature bit HEADER_BRANCH_STACK to mark the
>> presence of branch stacks in samples.
>>
>> You can now do:
>> $ perf record -b any noploop 2
>> $ perf report
>> # Events: 8K cycles
>> #
>> # Overhead Command Source Shared Object Source Symbol Target
>> Shared Object Target Symbol
>> # ........ ....... .................... ...................
>> .................... ..................
>> #
>> 91.56% noploop noploop [.] noploop
>> noploop [.] noploop
>> 0.42% noploop [kernel.kallsyms] [k] __lock_acquire
>> [kernel.kallsyms] [k] __lock_acquire
>>
>>
>> To force regular reporting based on the instruction address:
>> $ perf report --no-branch-stack
>> #
>> # Events: 2K cycles
>> #
>> # Overhead Command Shared Object Symbol
>> # ........ ....... ................. ...............................
>> #
>> 92.03% noploop noploop [.] noploop
>> 1.00% noploop [kernel.kallsyms] [k] lock_acquire
>>
>>
>> Signed-off-by: Stephane Eranian<eranian@...gle.com>
>> ---
>>
>> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
>> index 1c49d4e..5e833a2 100644
>> --- a/tools/perf/builtin-record.c
>> +++ b/tools/perf/builtin-record.c
>> @@ -473,6 +473,9 @@ static int __cmd_record(struct perf_record *rec, int
>> argc, const char **argv)
>> if (!have_tracepoints(&evsel_list->entries))
>> perf_header__clear_feat(&session->header,
>> HEADER_TRACE_INFO);
>>
>> + if (!rec->opts.branch_stack)
>> + perf_header__clear_feat(&session->header,
>> HEADER_BRANCH_STACK);
>
>
> branch tracing is user requested on, so shouldn't feature default off and
> only be enabled when requested?
>
Well, what Ingo was suggesting is that perf report auto-detects whether or
not branch mode is necessary by looking at the perf.data file. Most likely
if you've recorded with -b, you are interested in a branch mode view rather
that the instruction view (default). So all this does is elimintate the need
to pass -b to perf report to enable branch mode.
> David
>
>
>> +
>> if (!rec->file_new) {
>> err = perf_session__read_header(session, output);
>> if (err< 0)
>> diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
>> index 528789f..edd4289 100644
>> --- a/tools/perf/builtin-report.c
>> +++ b/tools/perf/builtin-report.c
>> @@ -306,21 +306,14 @@ static int __cmd_report(struct perf_report *rep)
>> {
>> int ret = -EINVAL;
>> u64 nr_samples;
>> - struct perf_session *session;
>> struct perf_evsel *pos;
>> + struct perf_session *session = rep->session;
>> struct map *kernel_map;
>> struct kmap *kernel_kmap;
>> const char *help = "For a higher level overview, try: perf report
>> --sort comm,dso";
>>
>> signal(SIGINT, sig_handler);
>>
>> - session = perf_session__new(rep->input_name, O_RDONLY,
>> - rep->force, false,&rep->tool);
>>
>> - if (session == NULL)
>> - return -ENOMEM;
>> -
>> - rep->session = session;
>> -
>> if (rep->cpu_list) {
>> ret = perf_session__cpu_bitmap(session, rep->cpu_list,
>> rep->cpu_bitmap);
>> @@ -489,7 +482,10 @@ parse_callchain_opt(const struct option *opt, const
>> char *arg, int unset)
>>
>> int cmd_report(int argc, const char **argv, const char *prefix __used)
>> {
>> + struct perf_session *session;
>> struct stat st;
>> + bool has_br_stack;
>> + int ret = -1;
>> char callchain_default_opt[] = "fractal,0.5,callee";
>> const char * const report_usage[] = {
>> "perf report [<options>]",
>> @@ -600,7 +596,23 @@ int cmd_report(int argc, const char **argv, const
>> char *prefix __used)
>> report.input_name = "perf.data";
>> }
>>
>> - if (sort__branch_mode) {
>> + session = perf_session__new(report.input_name, O_RDONLY,
>> + report.force, false,&report.tool);
>> + if (session == NULL)
>> + return -ENOMEM;
>> +
>> + report.session = session;
>> +
>> + has_br_stack = perf_header__has_feat(&session->header,
>> + HEADER_BRANCH_STACK);
>> +
>> + /*
>> + * if branch mode set by user via -b or --branch-stack
>> + * or not forced off by user (-no-branch-stack) user and present
>> + * in the file then we set branch mode
>> + */
>> + if (sort__branch_mode || (sort__branch_mode == -1&&
>> has_br_stack)) {
>>
>> + sort__branch_mode = true;
>> if (use_browser)
>> fprintf(stderr, "Warning: TUI interface not
>> supported"
>> " in branch mode\n");
>> @@ -657,13 +669,13 @@ int cmd_report(int argc, const char **argv, const
>> char *prefix __used)
>> }
>>
>> if (symbol__init()< 0)
>> - return -1;
>> + goto error;
>>
>> setup_sorting(report_usage, options);
>>
>> if (parent_pattern != default_parent_pattern) {
>> if (sort_dimension__add("parent")< 0)
>> - return -1;
>> + goto error;
>>
>> /*
>> * Only show the parent fields if we explicitly
>> @@ -685,5 +697,8 @@ int cmd_report(int argc, const char **argv, const char
>> *prefix __used)
>> sort_entry__setup_elide(&sort_comm, symbol_conf.comm_list, "comm",
>> stdout);
>> sort_entry__setup_elide(&sort_sym, symbol_conf.sym_list, "symbol",
>> stdout);
>>
>> - return __cmd_report(&report);
>> + ret = __cmd_report(&report);
>> +error:
>> + perf_session__delete(session);
>> + return ret;
>> }
>> diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
>> index c851495..c22491e 100644
>> --- a/tools/perf/util/header.c
>> +++ b/tools/perf/util/header.c
>> @@ -1023,6 +1023,12 @@ static int write_cpuid(int fd, struct perf_header
>> *h __used,
>> return do_write_string(fd, buffer);
>> }
>>
>> +static int write_branch_stack(int fd __used, struct perf_header *h
>> __used,
>> + struct perf_evlist *evlist __used)
>> +{
>> + return 0;
>> +}
>> +
>> static void print_hostname(struct perf_header *ph, int fd, FILE *fp)
>> {
>> char *str = do_read_string(fd, ph);
>> @@ -1315,6 +1321,12 @@ static void print_cpuid(struct perf_header *ph, int
>> fd, FILE *fp)
>> free(str);
>> }
>>
>> +static void print_branch_stack(struct perf_header *ph __used, int fd
>> __used,
>> + FILE *fp)
>> +{
>> + fprintf(fp, "# contains samples with branch stacks\n");
>> +}
>> +
>> static int __event_process_build_id(struct build_id_event *bev,
>> char *filename,
>> struct perf_session *session)
>> @@ -1519,6 +1531,7 @@ static const struct feature_ops
>> feat_ops[HEADER_LAST_FEATURE] = {
>> FEAT_OPA(HEADER_CMDLINE, cmdline),
>> FEAT_OPF(HEADER_CPU_TOPOLOGY, cpu_topology),
>> FEAT_OPF(HEADER_NUMA_TOPOLOGY, numa_topology),
>> + FEAT_OPA(HEADER_BRANCH_STACK, branch_stack),
>> };
>>
>> struct header_print_data {
>> diff --git a/tools/perf/util/header.h b/tools/perf/util/header.h
>> index e68f617..21a6be0 100644
>> --- a/tools/perf/util/header.h
>> +++ b/tools/perf/util/header.h
>> @@ -27,7 +27,7 @@ enum {
>> HEADER_EVENT_DESC,
>> HEADER_CPU_TOPOLOGY,
>> HEADER_NUMA_TOPOLOGY,
>> -
>> + HEADER_BRANCH_STACK,
>> HEADER_LAST_FEATURE,
>> HEADER_FEAT_BITS = 256,
>> };
>> diff --git a/tools/perf/util/sort.c b/tools/perf/util/sort.c
>> index 2739ed1..69d50c0 100644
>> --- a/tools/perf/util/sort.c
>> +++ b/tools/perf/util/sort.c
>> @@ -8,7 +8,7 @@ const char default_sort_order[] = "comm,dso,symbol";
>> const char *sort_order = default_sort_order;
>> int sort__need_collapse = 0;
>> int sort__has_parent = 0;
>> -bool sort__branch_mode;
>> +bool sort__branch_mode = -1; /* -1 = means not set */
>>
>> enum sort_type sort__first_dimension;
>>
>
--
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