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Perf can add a probe on kernel module which has not been loaded yet. The current implementation finds the module name from path. But if the filename is different from the actual module name then perf fails to register a probe while loading module because of mismatch in the names. For example, samples/kobject/kobject-example.ko is loaded as kobject_example. Before applying patch: $ sudo ./perf probe -m /linux/samples/kobject/kobject-example.ko foo_show Added new event: probe:foo_show (on foo_show in kobject-example) You can now use it in all perf tools, such as: perf record -e probe:foo_show -aR sleep 1 $ cat /sys/kernel/debug/tracing/kprobe_events p:probe/foo_show kobject-example:foo_show $ insmod kobject-example.ko $ lsmod Module Size Used by kobject_example 16384 0 Generate read to /sys/kernel/kobject_example/foo while recording data with below command $ sudo ./perf record -e probe:foo_show -a [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.093 MB perf.data ] $./perf report --stdio -F overhead,comm,dso,sym Error: The perf.data.old file has no samples! After applying patch: $ sudo ./perf probe -m /linux/samples/kobject/kobject-example.ko foo_show Added new event: probe:foo_show (on foo_show in kobject_example) You can now use it in all perf tools, such as: perf record -e probe:foo_show -aR sleep 1 $ sudo cat /sys/kernel/debug/tracing/kprobe_events p:probe/foo_show kobject_example:foo_show $ insmod kobject-example.ko $ lsmod Module Size Used by kobject_example 16384 0 Generate read to /sys/kernel/kobject_example/foo while recording data with below command $ sudo ./perf record -e probe:foo_show -a [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.097 MB perf.data (8 samples) ] $ sudo ./perf report --stdio -F overhead,comm,dso,sym ... # Samples: 8 of event 'probe:foo_show' # Event count (approx.): 8 # # Overhead Command Shared Object Symbol # ........ ....... ................. ............ # 100.00% cat [kobject_example] [k] foo_show Signed-off-by: Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com> Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Cc: Wang Nan <wangnan0@huawei.com> Link: http://lkml.kernel.org/r/1461680741-12517-2-git-send-email-ravi.bangoria@linux.vnet.ibm.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> |
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.. | ||
arch | ||
bench | ||
config | ||
Documentation | ||
jvmti | ||
python | ||
scripts | ||
tests | ||
trace | ||
ui | ||
util | ||
.gitignore | ||
Build | ||
builtin-annotate.c | ||
builtin-bench.c | ||
builtin-buildid-cache.c | ||
builtin-buildid-list.c | ||
builtin-config.c | ||
builtin-data.c | ||
builtin-diff.c | ||
builtin-evlist.c | ||
builtin-help.c | ||
builtin-inject.c | ||
builtin-kmem.c | ||
builtin-kvm.c | ||
builtin-list.c | ||
builtin-lock.c | ||
builtin-mem.c | ||
builtin-probe.c | ||
builtin-record.c | ||
builtin-report.c | ||
builtin-sched.c | ||
builtin-script.c | ||
builtin-stat.c | ||
builtin-timechart.c | ||
builtin-top.c | ||
builtin-trace.c | ||
builtin-version.c | ||
builtin.h | ||
command-list.txt | ||
CREDITS | ||
design.txt | ||
Makefile | ||
Makefile.perf | ||
MANIFEST | ||
perf-archive.sh | ||
perf-completion.sh | ||
perf-read-vdso.c | ||
perf-sys.h | ||
perf-with-kcore.sh | ||
perf.c | ||
perf.h |