Hi Masami,
I'm adding thread refcounting in perf, and in this process I am
investigating a problem, so thought about using perf itself to match
thread__get with thread__put:
[root@ssdandy ~]# perf probe -x ~/bin/perf -V thread__put
Available variables at thread__put
@<thread__put+0>
struct thread* thread
[root@ssdandy ~]# perf probe -x ~/bin/perf -V thread__get
Available variables at thread__get
@<thread__get+0>
struct thread* thread
[root@ssdandy ~]#
cool, so I thought it would be just a matter of asking to put the probes
and get the value of 'thread', then match things, but:
[root@ssdandy ~]# perf probe -v ~/bin/perf thread__put thread
probe-definition(0): thread__put thread
symbol:thread__put file:(null) line:0 offset:0 return:0 lazy:(null)
parsing arg: thread into thread
1 arguments
Open Debuginfo file: /root/bin/perf
Try to find probe point from debuginfo.
Probe point found: thread__put+0
Searching 'thread' variable in context.
Converting variable thread into trace event.
thread type is (null).
Found 1 probe_trace_events.
Opening /sys/kernel/debug/tracing/uprobe_events write=1
Added new event:
Writing event: p:probe_perf/thread__put /root/bin/perf:0xd03d2
thread=-32(%sp):u64
Failed to write event: Invalid argument
Error: Failed to add events. Reason: Invalid argument (Code: -22)
[root@ssdandy ~]#
Not possible :-\
please let me know if you need some file, here is the readelf -wi for
those two routines:
# readelf -wi ~/bin/perf
<SNIP>
<1><e25f1>: Abbrev Number: 35 (DW_TAG_subprogram)
<e25f2> DW_AT_external : 1
<e25f2> DW_AT_name : (indirect string, offset: 0x4c5c3):
thread__get
<e25f6> DW_AT_decl_file : 6
<e25f7> DW_AT_decl_line : 84
<e25f8> DW_AT_prototyped : 1
<e25f8> DW_AT_type : <0xe15cc>
<e25fc> DW_AT_low_pc : 0x4d038c
<e2604> DW_AT_high_pc : 0x46
<e260c> DW_AT_frame_base : 1 byte block: 9c (DW_OP_call_frame_cfa)
<e260e> DW_AT_GNU_all_tail_call_sites: 1
<e260e> DW_AT_sibling : <0xe2621>
<2><e2612>: Abbrev Number: 32 (DW_TAG_formal_parameter)
<e2613> DW_AT_name : (indirect string, offset: 0x43dc7): thread
<e2617> DW_AT_decl_file : 6
<e2618> DW_AT_decl_line : 84
<e2619> DW_AT_type : <0xe15cc>
<e261d> DW_AT_location : 2 byte block: 91 58 (DW_OP_fbreg: -40)
<2><e2620>: Abbrev Number: 0
<1><e2621>: Abbrev Number: 39 (DW_TAG_subprogram)
<e2622> DW_AT_external : 1
<e2622> DW_AT_name : (indirect string, offset: 0x4c699):
thread__put
<e2626> DW_AT_decl_file : 6
<e2627> DW_AT_decl_line : 90
<e2628> DW_AT_prototyped : 1
<e2628> DW_AT_low_pc : 0x4d03d2
<e2630> DW_AT_high_pc : 0x6c
<e2638> DW_AT_frame_base : 1 byte block: 9c (DW_OP_call_frame_cfa)
<e263a> DW_AT_GNU_all_tail_call_sites: 1
<e263a> DW_AT_sibling : <0xe264d>
<2><e263e>: Abbrev Number: 32 (DW_TAG_formal_parameter)
<e263f> DW_AT_name : (indirect string, offset: 0x43dc7): thread
<e2643> DW_AT_decl_file : 6
<e2644> DW_AT_decl_line : 90
<e2645> DW_AT_type : <0xe15cc>
<SNIP>
Will see what I can do with just:
[root@ssdandy ~]# perf probe ~/bin/perf thread__get
Added new event:
probe_perf:thread__get (on thread__get in /root/bin/perf)
You can now use it in all perf tools, such as:
perf record -e probe_perf:thread__get -aR sleep 1
[root@ssdandy ~]# perf probe ~/bin/perf thread__put
Added new event:
probe_perf:thread__put (on thread__put in /root/bin/perf)
You can now use it in all perf tools, such as:
perf record -e probe_perf:thread__put -aR sleep 1
[root@ssdandy ~]# perf list probe*:*
List of pre-defined events (to be used in -e):
probe_perf:thread__put [Tracepoint event]
probe_perf:thread__get [Tracepoint event]
[root@ssdandy ~]# perf probe -l
probe_perf:thread__get (on thread__get@util/thread.c in /root/bin/perf)
probe_perf:thread__put (on thread__put@util/thread.c in /root/bin/perf)
[root@ssdandy ~]#
- Arnaldo
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