Messages in this thread | | | Subject | [PATCH perf/core 0/6] perf-probe: Bugfix and add new options for cache | From | Masami Hiramatsu <> | Date | Fri, 31 Oct 2014 14:51:29 -0400 |
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Hi,
Here is a sereis of patches for enabling "event cache" feature to perf probe. Brendan gives me this cool idea, thanks! :)
In this series, I added following options/features; - --output option We can save the probe definition command for given probe-event instead of setting up the local tracing/kprobe_events.
- --no-inlines option We can avoid searching the inline functions in debuginfo. Usually useful with wildcards since the wildcards will hit a huge amount of probe-points.
- $params special probe argument $params is expanded to function parameters only, no locally defined variables. This is useful for function-call tracing.
- wildcard support for function name Wildcard support is the key feature for this idea. Now we can use '*foo*' for function name to define the probe-point.
So by using all of them, we can make an "event cache" file on all functions (except for inlined functions) as below.
# perf probe --max-probes=100000 --no-inlines -a '* $params' -o event.cache
builds "event.cache" file in which event settings for all function entries, like below;
p:probe/reset_early_page_tables _text+12980741 p:probe/copy_bootdata _text+12980830 real_mode_data=%di:u64 p:probe/exit_amd_microcode _text+14692680 p:probe/early_make_pgtable _text+12981274 address=%di:u64 p:probe/x86_64_start_reservations _text+12981700 real_mode_data=%di:u64 p:probe/x86_64_start_kernel _text+12981744 real_mode_data=%di:u64 p:probe/reserve_ebda_region _text+12982117
This event.cache file will be big (but much smaller than native debuginfo :) ) if your kernel have many option embedded. Anyway, you can compress it too.
# wc -l event.cache 33813 event.cache # ls -sh event.cache 2.3M event.cache # ls -sh event.cache.gz 464K event.cache.gz
For setting up a probe event, you can grep the function name and write it to tracing/kprobe_events, as below;
# zcat event.cache.gz | \ grep probe/vfs_symlink > /sys/kernel/debug/tracing/kprobe_events
This can be applied for the remote machine only if the machine runs on completely same kernel binary. Perhaps, we need some helper tool to check it.
Thank you,
---
Masami Hiramatsu (6): [BUGFIX] perf-probe: Fix to handle optimized not-inlined but has no instance [DOC] perf-probe: Update perf-probe document perf-probe: Add --output option to write commands in a standard file perf-probe: Add --no-inlines option to avoid searching inline functions perf-probe: Support $params special probe argument perf-probe: Support glob wildcards for function name
tools/perf/Documentation/perf-probe.txt | 25 ++++++++++ tools/perf/builtin-probe.c | 32 +++++++++++++ tools/perf/util/dwarf-aux.c | 31 +++++++++++++ tools/perf/util/dwarf-aux.h | 6 +++ tools/perf/util/probe-event.c | 73 +++++++++++++++++++++++-------- tools/perf/util/probe-event.h | 4 +- tools/perf/util/probe-finder.c | 74 +++++++++++++++++++------------ tools/perf/util/probe-finder.h | 6 ++- tools/perf/util/util.h | 4 ++ 9 files changed, 202 insertions(+), 53 deletions(-)
-- Masami HIRAMATSU Software Platform Research Dpt. Linux Technology Center Hitachi, Ltd., Yokohama Research Laboratory E-mail: masami.hiramatsu.pt@hitachi.com
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