diff options
Diffstat (limited to 'tools/perf/Documentation/perf-probe.txt')
| -rw-r--r-- | tools/perf/Documentation/perf-probe.txt | 23 |
1 files changed, 18 insertions, 5 deletions
diff --git a/tools/perf/Documentation/perf-probe.txt b/tools/perf/Documentation/perf-probe.txt index ed3ecfa422e1..5c43a6edc0e5 100644 --- a/tools/perf/Documentation/perf-probe.txt +++ b/tools/perf/Documentation/perf-probe.txt @@ -57,7 +57,7 @@ OPTIONS -q:: --quiet:: - Be quiet (do not show any messages including errors). + Do not show any warnings or messages. Can not use with -v. -a:: @@ -222,11 +222,11 @@ probe syntax, 'SRC' means the source file path, 'ALN' is start line number, and 'ALN2' is end line number in the file. It is also possible to specify how many lines to show by using 'NUM'. Moreover, 'FUNC@SRC' combination is good for searching a specific function when several functions share same name. -So, "source.c:100-120" shows lines between 100th to l20th in source.c file. And "func:10+20" shows 20 lines from 10th line of func function. +So, "source.c:100-120" shows lines between 100th to 120th in source.c file. And "func:10+20" shows 20 lines from 10th line of func function. LAZY MATCHING ------------- - The lazy line matching is similar to glob matching but ignoring spaces in both of pattern and target. So this accepts wildcards('*', '?') and character classes(e.g. [a-z], [!A-Z]). +The lazy line matching is similar to glob matching but ignoring spaces in both of pattern and target. So this accepts wildcards('*', '?') and character classes(e.g. [a-z], [!A-Z]). e.g. 'a=*' can matches 'a=b', 'a = b', 'a == b' and so on. @@ -235,8 +235,8 @@ This provides some sort of flexibility and robustness to probe point definitions FILTER PATTERN -------------- - The filter pattern is a glob matching pattern(s) to filter variables. - In addition, you can use "!" for specifying filter-out rule. You also can give several rules combined with "&" or "|", and fold those rules as one rule by using "(" ")". +The filter pattern is a glob matching pattern(s) to filter variables. +In addition, you can use "!" for specifying filter-out rule. You also can give several rules combined with "&" or "|", and fold those rules as one rule by using "(" ")". e.g. With --filter "foo* | bar*", perf probe -V shows variables which start with "foo" or "bar". @@ -295,6 +295,19 @@ Add a probe in a source file using special characters by backslash escape ./perf probe -x /opt/test/a.out 'foo\+bar.c:4' +PERMISSIONS AND SYSCTL +---------------------- +Since perf probe depends on ftrace (tracefs) and kallsyms (/proc/kallsyms), you have to care about the permission and some sysctl knobs. + + - Since tracefs and kallsyms requires root or privileged user to access it, the following perf probe commands also require it; --add, --del, --list (except for --cache option) + + - The system admin can remount the tracefs with 755 (`sudo mount -o remount,mode=755 /sys/kernel/tracing/`) to allow unprivileged user to run the perf probe --list command. + + - /proc/sys/kernel/kptr_restrict = 2 (restrict all users) also prevents perf probe to retrieve the important information from kallsyms. You also need to set to 1 (restrict non CAP_SYSLOG users) for the above commands. Since the user-space probe doesn't need to access kallsyms, this is only for probing the kernel function (kprobes). + + - Since the perf probe commands read the vmlinux (for kernel) and/or the debuginfo file (including user-space application), you need to ensure that you can read those files. + + SEE ALSO -------- linkperf:perf-trace[1], linkperf:perf-record[1], linkperf:perf-buildid-cache[1] |