Hi Masami,
On 07/15/2015 02:43 PM, Masami Hiramatsu wrote:
Hi,
Here is the 2nd version of the patchset for probe-cache and
initial SDT support which are going to be perf-cache finally.
Thanks for adding the SDT support.
The perf-probe is useful for debugging, but it strongly depends
on the debuginfo. Without debuginfo, it is just a frontend of
ftrace's dynamic events. This can usually happen in server
farms or on cloud system, since no one wants to distribute
big debuginfo packages.
To solve this issue, I had tried to make a pre-analyzed probes
( https://lkml.org/lkml/2014/10/31/207 ) but it has a problm
that we can't ensure the probed binary is same as what we analyzed.
Arnaldo gave me an idea to reuse build-id cache for that perpose
and this series is the first prototype of that.
At the same time, Hemant has started to support SDT probes which
also use the cache file of SDT info. So I decided to merge this
into the same build-id cache.
In this version, SDT support is still very limited, it works
as a part of probe-cache.
In this version, perf probe supports --cache option which means
that perf probe manipulate probe caches, for example,
# perf probe --cache --add "probe-desc"
does not only add probe events but also add "probe-desc" and
it's result on the cache. (Note that the cached entry is always
referred even without --cache)
The --list and --del commands also support --cache. Note that
both are only manipulate caches, not real events.
To use SDT, we have to scan the target binary at first by using
perf-buildid-cache, e.g.
# perf buildid-cache --add /lib/libc-2.17.so
And perf probe --cache --list shows what SDTs are scanned.
# perf probe --cache --list
/usr/lib/libc-2.17.so (a6fb821bdf53660eb2c29f778757aef294d3d392):
libc:setjmp=setjmp
libc:longjmp=longjmp
libc:longjmp_target=longjmp_target
libc:memory_heap_new=memory_heap_new
libc:memory_sbrk_less=memory_sbrk_less
libc:memory_arena_reuse_free_list=memory_arena_reuse_free_list
libc:memory_arena_reuse=memory_arena_reuse
...
To use the SDT events, perf probe -x BIN %SDTEVENT allows you to
add a probe on SDTEVENT@BIN.
# perf probe -x /lib/libc-2.17.so %memory_heap_new
If you define a cached probe with event name, you can also reuse
it as same as SDT events.
# perf probe -x ./perf --cache -n 'myevent=dso__load $params'
(Note that "-n" option only updates caches)
To use the above "myevent", you just have to add "%myevent".
# perf probe -x ./perf %myevent
TODOs:
- Show available cached/SDT events by perf-list
- Allow perf-record to use cached/SDT events directly
As I was already working on SDT events' recording
https://lkml.org/lkml/2014/11/2/73,
I can re-spin the patches on top of your patchset and make the
required changes to implement the above TODOs.
What would you suggest?
Thank you,
---
Hemant Kumar (1):
perf/sdt: ELF support for SDT
Masami Hiramatsu (15):
perf probe: Simplify __add_probe_trace_events code
perf probe: Move ftrace probe-event operations to probe-file.c
perf probe: Use strbuf for making strings in probe-event.c
perf-buildid-cache: Use path/to/bin/buildid/elf instead of
path/to/bin/buildid
perf buildid: Use SBUILD_ID_SIZE macro
perf buildid: Introduce sysfs/filename__sprintf_build_id
perf: Add lsdir to read a directory
perf-buildid-cache: Use lsdir for looking up buildid caches
perf probe: Add --cache option to cache the probe definitions
perf probe: Use cache entry if possible
perf probe: Show all cached probes
perf probe: Remove caches when --cache is given
perf probe: Add group name support
perf buildid-cache: Scan and import user SDT events to probe cache
perf probe: Accept %sdt and %cached event name
tools/perf/Documentation/perf-probe.txt | 14
tools/perf/builtin-buildid-cache.c | 22 -
tools/perf/builtin-buildid-list.c | 28 -
tools/perf/builtin-probe.c | 3
tools/perf/util/Build | 1
tools/perf/util/build-id.c | 230 ++++++--
tools/perf/util/build-id.h | 11
tools/perf/util/dso.h | 5
tools/perf/util/probe-event.c | 918 ++++++++++++++-----------------
tools/perf/util/probe-event.h | 16 -
tools/perf/util/probe-file.c | 763 ++++++++++++++++++++++++++
tools/perf/util/probe-file.h | 46 ++
tools/perf/util/probe-finder.c | 10
tools/perf/util/symbol-elf.c | 252 +++++++++
tools/perf/util/symbol.c | 2
tools/perf/util/symbol.h | 22 +
tools/perf/util/util.c | 34 +
tools/perf/util/util.h | 4
18 files changed, 1781 insertions(+), 600 deletions(-)
create mode 100644 tools/perf/util/probe-file.c
create mode 100644 tools/perf/util/probe-file.h
--
Thanks,
Hemant Kumar
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