diff options
| author | Namhyung Kim <namhyung@kernel.org> | 2025-11-20 15:48:01 -0800 |
|---|---|---|
| committer | Namhyung Kim <namhyung@kernel.org> | 2025-12-02 21:59:13 -0800 |
| commit | 27ddc1d7a6b79ae76f5c07af293fde966da8221b (patch) | |
| tree | 9c7e1852bee936719a91c9ba30c94b602ff34820 /tools/perf/Documentation | |
| parent | f4e3381648be205365cb475512ee536e108e060e (diff) | |
perf record: Add --call-graph fp,defer option for deferred callchains
Add a new callchain record mode option for deferred callchains. For now
it only works with FP (frame-pointer) mode.
And add the missing feature detection logic to clear the flag on old
kernels.
$ perf record --call-graph fp,defer -vv true
...
------------------------------------------------------------
perf_event_attr:
type 0 (PERF_TYPE_HARDWARE)
size 136
config 0 (PERF_COUNT_HW_CPU_CYCLES)
{ sample_period, sample_freq } 4000
sample_type IP|TID|TIME|CALLCHAIN|PERIOD
read_format ID|LOST
disabled 1
inherit 1
mmap 1
comm 1
freq 1
enable_on_exec 1
task 1
sample_id_all 1
mmap2 1
comm_exec 1
ksymbol 1
bpf_event 1
defer_callchain 1
defer_output 1
------------------------------------------------------------
sys_perf_event_open: pid 162755 cpu 0 group_fd -1 flags 0x8
sys_perf_event_open failed, error -22
switching off deferred callchain support
Reviewed-by: Ian Rogers <irogers@google.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Diffstat (limited to 'tools/perf/Documentation')
| -rw-r--r-- | tools/perf/Documentation/perf-config.txt | 3 | ||||
| -rw-r--r-- | tools/perf/Documentation/perf-record.txt | 4 |
2 files changed, 7 insertions, 0 deletions
diff --git a/tools/perf/Documentation/perf-config.txt b/tools/perf/Documentation/perf-config.txt index c6f335659667..642d1c490d9e 100644 --- a/tools/perf/Documentation/perf-config.txt +++ b/tools/perf/Documentation/perf-config.txt @@ -452,6 +452,9 @@ call-graph.*:: kernel space is controlled not by this option but by the kernel config (CONFIG_UNWINDER_*). + The 'defer' mode can be used with 'fp' mode to enable deferred + user callchains (like 'fp,defer'). + call-graph.dump-size:: The size of stack to dump in order to do post-unwinding. Default is 8192 (byte). When using dwarf into record-mode, the default size will be used if omitted. diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt index 067891bd7da6..e8b9aadbbfa5 100644 --- a/tools/perf/Documentation/perf-record.txt +++ b/tools/perf/Documentation/perf-record.txt @@ -325,6 +325,10 @@ OPTIONS by default. User can change the number by passing it after comma like "--call-graph fp,32". + Also "defer" can be used with "fp" (like "--call-graph fp,defer") to + enable deferred user callchain which will collect user-space callchains + when the thread returns to the user space. + -q:: --quiet:: Don't print any warnings or messages, useful for scripting. |