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| author | Vince Weaver <vincent.weaver@maine.edu> | 2016-10-13 17:16:16 -0400 |
|---|---|---|
| committer | Michael Kerrisk <mtk.manpages@gmail.com> | 2016-10-14 12:31:59 +0200 |
| commit | fd133d5dc4c433edc04e412e62c537e9e01a9fc5 (patch) | |
| tree | 259a936181b512b26fe2ae057a58977eb589c23e /man2 | |
| parent | ca8b1e32a9871cd1bd0d12d006daa2478b3f02de (diff) | |
| download | man-pages-fd133d5dc4c433edc04e412e62c537e9e01a9fc5.tar.gz | |
perf_event_open.2: Document sample_max_stack and /proc/sys/kernel/perf_event_max_stack
Linux 4.8 added a new sample_max_stack parameter, as well as
/proc/sys/kernel/perf_event_max_stack which limits it and a new
EOVERFLOW error return.
Signed-off-by: Vince Weaver <vincent.weaver@maine.edu>
Diffstat (limited to 'man2')
| -rw-r--r-- | man2/perf_event_open.2 | 29 |
1 files changed, 28 insertions, 1 deletions
diff --git a/man2/perf_event_open.2 b/man2/perf_event_open.2 index 3c894ccd12..8c8763b402 100644 --- a/man2/perf_event_open.2 +++ b/man2/perf_event_open.2 @@ -268,7 +268,8 @@ struct perf_event_attr { __s32 clockid; /* clock to use for time fields */ __u64 sample_regs_intr; /* regs to dump on samples */ __u32 aux_watermark; /* aux bytes before wakeup */ - __u32 __reserved_2; /* align to u64 */ + __u16 sample_max_stack; /* max frames in callchain */ + __u16 __reserved_2; /* align to u64 */ }; .fi @@ -1307,6 +1308,15 @@ currently supported. This specifies how much data is required to trigger a .B PERF_RECORD_AUX sample. +.TP +.IR "sample_max_stack" " (since Linux 4.8)" +.\" commit 97c79a38cd454602645f0470ffb444b3b75ce574 +When +.I sample_type +includes +.B PERF_SAMPLE_CALLCHAIN +this specifies how many stack frames to report when +generating the callchain. .SS Reading results Once a .BR perf_event_open () @@ -2780,6 +2790,14 @@ users to sample at a rate that impacts overall machine performance and potentially lock up the machine. The default value is 100000 (samples per second). + +.TP +.I /proc/sys/kernel/perf_event_max_stack +.\" Introduced in c5dfd78eb79851e278b7973031b9ca363da87a7e + +This sets the maximum depth of stack frame entries reported +when generating a call trace. + .TP .I /proc/sys/kernel/perf_event_mlock_kb @@ -3001,6 +3019,15 @@ This includes requesting low-skid events if not supported, branch tracing if it is not available, sampling if no PMU interrupt is available, and branch stacks for software events. .TP +.BR EOVERFLOW " (since Linux 4.8)" +.\" 97c79a38cd454602645f0470ffb444b3b75ce574 +Returned if +.B PERF_SAMPLE_CALLCHAIN +is requested and +.I sample_max_stack +is larger than the maximum specified in +.IR /proc/sys/kernel/perf_event_max_stack . +.TP .B EPERM Returned on many (but not all) architectures when an unsupported .IR exclude_hv ", " exclude_idle ", " exclude_user ", or " exclude_kernel |