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Subject[PATCH 02/44] perf record: Allow to limit number of reported perf.data files
Date
From: Andi Kleen <ak@linux.intel.com>

When doing long term recording and waiting for some event to snapshot
on, we often only care about the last minute or so.

The --switch-output command line option supports rotating the perf.data
file when the size exceeds a threshold. But the disk would still be
filled with unnecessary old files.

Add a new option to only keep a number of rotated files, so that the
disk space usage can be limited.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
LPU-Reference: 20190314225002.30108-3-andi@firstfloor.org
Link: https://lkml.kernel.org/n/tip-y5u2lik0ragt4vlktz6qc9ks@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/Documentation/perf-record.txt | 4 ++++
tools/perf/builtin-record.c | 30 +++++++++++++++++++++++-
tools/perf/util/data.c | 11 ++++-----
tools/perf/util/data.h | 2 +-
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);
--
2.20.1
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