4 files changed, 39 insertions, 8 deletions

diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt
index 8f0c2be34848..8fe4dffcadd0 100644
--- a/tools/perf/Documentation/perf-record.txt
+++ b/tools/perf/Documentation/perf-record.txt
@@ -495,6 +495,10 @@ overhead. You can still switch them on with:
 
   --switch-output --no-no-buildid  --no-no-buildid-cache
 
+--switch-max-files=N::
+
+When rotating perf.data with --switch-output, only keep N files.
+
 --dry-run::
 Parse options then exit. --dry-run can be used to detect errors in cmdline
 options.
diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
index a468d882e74f..02d7c40b2d10 100644
--- a/tools/perf/builtin-record.c
+++ b/tools/perf/builtin-record.c
@@ -62,6 +62,9 @@ struct switch_output {
         unsigned long    time;
         const char      *str;
         bool             set;
+        char             **filenames;
+        int              num_files;
+        int              cur_file;
 };
 
 struct record {
@@ -892,6 +895,7 @@ record__switch_output(struct record *rec, bool at_exit)
 {
         struct perf_data *data = &rec->data;
         int fd, err;
+        char *new_filename;
 
         /* Same Size:      "2015122520103046"*/
         char timestamp[] = "InvalidTimestamp";
@@ -912,7 +916,7 @@ record__switch_output(struct record *rec, bool at_exit)
 
         fd = perf_data__switch(data, timestamp,
                                     rec->session->header.data_offset,
-                                    at_exit);
+                                    at_exit, &new_filename);
         if (fd >= 0 && !at_exit) {
                 rec->bytes_written = 0;
                 rec->session->header.data_size = 0;
@@ -922,6 +926,21 @@ record__switch_output(struct record *rec, bool at_exit)
                 fprintf(stderr, "[ perf record: Dump %s.%s ]\n",
                         data->path, timestamp);
 
+        if (rec->switch_output.num_files) {
+                int n = rec->switch_output.cur_file + 1;
+
+                if (n >= rec->switch_output.num_files)
+                        n = 0;
+                rec->switch_output.cur_file = n;
+                if (rec->switch_output.filenames[n]) {
+                        remove(rec->switch_output.filenames[n]);
+                        free(rec->switch_output.filenames[n]);
+                }
+                rec->switch_output.filenames[n] = new_filename;
+        } else {
+                free(new_filename);
+        }
+
         /* Output tracking events */
         if (!at_exit) {
                 record__synthesize(rec, false);
@@ -1973,6 +1992,8 @@ static struct option __record_options[] = {
                           &record.switch_output.set, "signal,size,time",
                           "Switch output when receive SIGUSR2 or cross size,time threshold",
                           "signal"),
+        OPT_INTEGER(0, "switch-max-files", &record.switch_output.num_files,
+                   "Limit number of switch output generated files"),
         OPT_BOOLEAN(0, "dry-run", &dry_run,
                     "Parse options then exit"),
 #ifdef HAVE_AIO_SUPPORT
@@ -2059,6 +2080,13 @@ int cmd_record(int argc, const char **argv)
                 alarm(rec->switch_output.time);
         }
 
+        if (rec->switch_output.num_files) {
+                rec->switch_output.filenames = calloc(sizeof(char *),
+                                                      rec->switch_output.num_files);
+                if (!rec->switch_output.filenames)
+                        return -EINVAL;
+        }
+
         /*
          * Allow aliases to facilitate the lookup of symbols for address
          * filters. Refer to auxtrace_parse_filters().
diff --git a/tools/perf/util/data.c b/tools/perf/util/data.c
index c6b67efea11a..6a64f713710d 100644
--- a/tools/perf/util/data.c
+++ b/tools/perf/util/data.c
@@ -361,9 +361,9 @@ ssize_t perf_data__write(struct perf_data *data,
 
 int perf_data__switch(struct perf_data *data,
                            const char *postfix,
-                           size_t pos, bool at_exit)
+                           size_t pos, bool at_exit,
+                           char **new_filepath)
 {
-        char *new_filepath;
         int ret;
 
         if (check_pipe(data))
@@ -371,15 +371,15 @@ int perf_data__switch(struct perf_data *data,
         if (perf_data__is_read(data))
                 return -EINVAL;
 
-        if (asprintf(&new_filepath, "%s.%s", data->path, postfix) < 0)
+        if (asprintf(new_filepath, "%s.%s", data->path, postfix) < 0)
                 return -ENOMEM;
 
         /*
          * Only fire a warning, don't return error, continue fill
          * original file.
          */
-        if (rename(data->path, new_filepath))
-                pr_warning("Failed to rename %s to %s\n", data->path, new_filepath);
+        if (rename(data->path, *new_filepath))
+                pr_warning("Failed to rename %s to %s\n", data->path, *new_filepath);
 
         if (!at_exit) {
                 close(data->file.fd);
@@ -396,7 +396,6 @@ int perf_data__switch(struct perf_data *data,
         }
         ret = data->file.fd;
 out:
-        free(new_filepath);
         return ret;
 }
 
diff --git a/tools/perf/util/data.h b/tools/perf/util/data.h
index 6aef8746469f..259868a39019 100644
--- a/tools/perf/util/data.h
+++ b/tools/perf/util/data.h
@@ -70,7 +70,7 @@ ssize_t perf_data_file__write(struct perf_data_file *file,
  */
 int perf_data__switch(struct perf_data *data,
                            const char *postfix,
-                           size_t pos, bool at_exit);
+                           size_t pos, bool at_exit, char **new_filepath);
 
 int perf_data__create_dir(struct perf_data *data, int nr);
 int perf_data__open_dir(struct perf_data *data);