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Message-ID: <4F47ABAD.9080408@gmail.com>
Date: Fri, 24 Feb 2012 08:24:29 -0700
From: David Ahern <dsahern@...il.com>
To: Stephane Eranian <eranian@...gle.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 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?
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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