perf record: Introduce --control fd:ctl-fd[,ack-fd] options

Introduce --control fd:ctl-fd[,ack-fd] options to pass open file
descriptors numbers from command line.

Extend perf-record.txt file with --control fd:ctl-fd[,ack-fd] options
description.

Document possible usage model introduced by --control fd:ctl-fd[,ack-fd]
options by providing example bash shell script.

Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/8dc01e1a-3a80-3f67-5385-4bc7112b0dd3@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt
index a843766..3f72d8e 100644 (file)
--- a/tools/perf/Documentation/perf-record.txt
+++ b/tools/perf/Documentation/perf-record.txt
@@ -627,6 +627,45 @@ option. The -e option and this one can be mixed and matched.  Events
 can be grouped using the {} notation.
 endif::HAVE_LIBPFM[]
 
+--control fd:ctl-fd[,ack-fd]
+Listen on ctl-fd descriptor for command to control measurement ('enable': enable events,
+'disable': disable events). Measurements can be started with events disabled using
+--delay=-1 option. Optionally send control command completion ('ack\n') to ack-fd descriptor
+to synchronize with the controlling process. Example of bash shell script to enable and
+disable events during measurements:
+
+#!/bin/bash
+
+ctl_dir=/tmp/
+
+ctl_fifo=${ctl_dir}perf_ctl.fifo
+test -p ${ctl_fifo} && unlink ${ctl_fifo}
+mkfifo ${ctl_fifo}
+exec {ctl_fd}<>${ctl_fifo}
+
+ctl_ack_fifo=${ctl_dir}perf_ctl_ack.fifo
+test -p ${ctl_ack_fifo} && unlink ${ctl_ack_fifo}
+mkfifo ${ctl_ack_fifo}
+exec {ctl_fd_ack}<>${ctl_ack_fifo}
+
+perf record -D -1 -e cpu-cycles -a               \
+            --control fd:${ctl_fd},${ctl_fd_ack} \
+            -- sleep 30 &
+perf_pid=$!
+
+sleep 5  && echo 'enable' >&${ctl_fd} && read -u ${ctl_fd_ack} e1 && echo "enabled(${e1})"
+sleep 10 && echo 'disable' >&${ctl_fd} && read -u ${ctl_fd_ack} d1 && echo "disabled(${d1})"
+
+exec {ctl_fd_ack}>&-
+unlink ${ctl_ack_fifo}
+
+exec {ctl_fd}>&-
+unlink ${ctl_fifo}
+
+wait -n ${perf_pid}
+exit $?
+
+
 SEE ALSO
 --------
 linkperf:perf-stat[1], linkperf:perf-list[1], linkperf:perf-intel-pt[1]

diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index 739601e..42978ff 100644 (file)
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -1786,6 +1786,9 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
                perf_evlist__start_workload(rec->evlist);
        }
 
+       if (evlist__initialize_ctlfd(rec->evlist, opts->ctl_fd, opts->ctl_fd_ack))
+               goto out_child;
+
        if (opts->initial_delay) {
                pr_info(EVLIST_DISABLED_MSG);
                if (opts->initial_delay > 0) {
@@ -1932,6 +1935,7 @@ static int __cmd_record(struct record *rec, int argc, const char **argv)
                record__synthesize_workload(rec, true);
 
 out_child:
+       evlist__finalize_ctlfd(rec->evlist);
        record__mmap_read_all(rec, true);
        record__aio_mmap_read_sync(rec);
 
@@ -2281,6 +2285,33 @@ out_free:
        return ret;
 }
 
+static int parse_control_option(const struct option *opt,
+                               const char *str,
+                               int unset __maybe_unused)
+{
+       char *comma = NULL, *endptr = NULL;
+       struct record_opts *config = (struct record_opts *)opt->value;
+
+       if (strncmp(str, "fd:", 3))
+               return -EINVAL;
+
+       config->ctl_fd = strtoul(&str[3], &endptr, 0);
+       if (endptr == &str[3])
+               return -EINVAL;
+
+       comma = strchr(str, ',');
+       if (comma) {
+               if (endptr != comma)
+                       return -EINVAL;
+
+               config->ctl_fd_ack = strtoul(comma + 1, &endptr, 0);
+               if (endptr == comma + 1 || *endptr != '\0')
+                       return -EINVAL;
+       }
+
+       return 0;
+}
+
 static void switch_output_size_warn(struct record *rec)
 {
        u64 wakeup_size = evlist__mmap_size(rec->opts.mmap_pages);
@@ -2417,6 +2448,8 @@ static struct record record = {
                },
                .mmap_flush          = MMAP_FLUSH_DEFAULT,
                .nr_threads_synthesize = 1,
+               .ctl_fd              = -1,
+               .ctl_fd_ack          = -1,
        },
        .tool = {
                .sample         = process_sample_event,
@@ -2618,6 +2651,10 @@ static struct option __record_options[] = {
                "libpfm4 event selector. use 'perf list' to list available events",
                parse_libpfm_events_option),
 #endif
+       OPT_CALLBACK(0, "control", &record.opts, "fd:ctl-fd[,ack-fd]",
+                    "Listen on ctl-fd descriptor for command to control measurement ('enable': enable events, 'disable': disable events).\n"
+                    "\t\t\t  Optionally send control command completion ('ack\\n') to ack-fd descriptor.",
+                     parse_control_option),
        OPT_END()
 };
 

diff --git a/tools/perf/util/record.h b/tools/perf/util/record.h
index e9b3842..03678ff 100644 (file)
--- a/tools/perf/util/record.h
+++ b/tools/perf/util/record.h
@@ -71,6 +71,8 @@ struct record_opts {
        int           mmap_flush;
        unsigned int  comp_level;
        unsigned int  nr_threads_synthesize;
+       int           ctl_fd;
+       int           ctl_fd_ack;
 };
 
 extern const char * const *record_usage;