The patch adds a new option to limit the output file size, then based on it, we can create a wrapper of the perf command that uses the option to avoid exhausting the disk space by the unconscious user.
Testing it: # ./perf record -a --max-size 100M Couldn't synthesize bpf events. WARNING: The perf data has already reached the limit, stop recording! WARNING: The perf data has already reached the limit, stop recording! WARNING: The perf data has already reached the limit, stop recording! WARNING: The perf data has already reached the limit, stop recording! WARNING: The perf data has already reached the limit, stop recording! WARNING: The perf data has already reached the limit, stop recording! WARNING: The perf data has already reached the limit, stop recording! WARNING: The perf data has already reached the limit, stop recording! [ perf record: Woken up 392 times to write data ] [ perf record: Captured and wrote 100.104 MB perf.data (2128267 samples) ] Terminated # ls -lh perf.data -rw------- 1 root root 101M Mar 11 14:48 perf.data Signed-off-by: Jiwei Sun <[email protected]> --- v3 changes: - add a test result - add the new option to tools/perf/Documentation/perf-record.txt v2 changes: - make patch based on latest Arnaldo's perf/core, - display warning message when reached the limit. --- tools/perf/Documentation/perf-record.txt | 3 ++ tools/perf/builtin-record.c | 42 ++++++++++++++++++++++++ 2 files changed, 45 insertions(+) diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt index 8f0c2be34848..731dcfabe7fa 100644 --- a/tools/perf/Documentation/perf-record.txt +++ b/tools/perf/Documentation/perf-record.txt @@ -524,6 +524,9 @@ config terms. For example: 'cycles/overwrite/' and 'instructions/no-overwrite/'. Implies --tail-synthesize. +--max-size:: +Limit the output data max size. + SEE ALSO -------- linkperf:perf-stat[1], linkperf:perf-list[1] diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c index a468d882e74f..fe0e87781841 100644 --- a/tools/perf/builtin-record.c +++ b/tools/perf/builtin-record.c @@ -83,6 +83,7 @@ struct record { struct switch_output switch_output; unsigned long long samples; cpu_set_t affinity_mask; + unsigned long output_max_size; /* = 0: unlimited */ }; static volatile int auxtrace_record__snapshot_started; @@ -112,6 +113,12 @@ static bool switch_output_time(struct record *rec) trigger_is_ready(&switch_output_trigger); } +static bool record__output_max_size_exceeded(struct record *rec) +{ + return (rec->output_max_size && + rec->bytes_written >= rec->output_max_size); +} + static int record__write(struct record *rec, struct perf_mmap *map __maybe_unused, void *bf, size_t size) { @@ -124,6 +131,12 @@ static int record__write(struct record *rec, struct perf_mmap *map __maybe_unuse rec->bytes_written += size; + if (record__output_max_size_exceeded(rec)) { + pr_warning("WARNING: The perf data has already reached " + "the limit, stop recording!\n"); + raise(SIGTERM); + } + if (switch_output_size(rec)) trigger_hit(&switch_output_trigger); @@ -1672,6 +1685,33 @@ static int record__parse_affinity(const struct option *opt, const char *str, int return 0; } +static int parse_output_max_size(const struct option *opt, + const char *str, int unset) +{ + unsigned long *s = (unsigned long *)opt->value; + static struct parse_tag tags_size[] = { + { .tag = 'B', .mult = 1 }, + { .tag = 'K', .mult = 1 << 10 }, + { .tag = 'M', .mult = 1 << 20 }, + { .tag = 'G', .mult = 1 << 30 }, + { .tag = 0 }, + }; + unsigned long val; + + if (unset) { + *s = 0; + return 0; + } + + val = parse_tag_value(str, tags_size); + if (val != (unsigned long) -1) { + *s = val; + return 0; + } + + return -1; +} + static int record__parse_mmap_pages(const struct option *opt, const char *str, int unset __maybe_unused) @@ -1983,6 +2023,8 @@ static struct option __record_options[] = { OPT_CALLBACK(0, "affinity", &record.opts, "node|cpu", "Set affinity mask of trace reading thread to NUMA node cpu mask or cpu of processed mmap buffer", record__parse_affinity), + OPT_CALLBACK(0, "max-size", &record.output_max_size, + "size", "Limit the maximum size of the output file", parse_output_max_size), OPT_END() }; -- 2.20.1
