result is null

[dingjingzhen]

@agentzh hi，I admire you for a long time,but now i have a question that when i use your tools generated file is empty, the project is a multithreaded program, can you give me some advice?
[root@Thor offcpu]# ./sample-bt -p 44833 -t 5 -u>a.bt
WARNING: Tracing 44833 (/home/second/test/bin/linux/x86_64/Test) in user-space only...
WARNING: Missing unwind data for a module, rerun with 'stap -d (unknown; retry with -DDEBUG_UNWIND)'
WARNING: _stp_read_address failed to access memory location
ERROR: probe overhead exceeded threshold
WARNING: Number of errors: 1, skipped probes: 57
WARNING: /usr/bin/staprun exited with status: 1
Pass 5: run failed. [man error::pass5]

[agentzh]

@dingjingzhen Try reducing the sampling time period and/or adding the command-line option -DSTP_NO_OVERLOAD to the stap command line inside the tool's source file.

[dingjingzhen]

@agentzh Ok, I have already solved the problem, but if I shorten the sampling time, whether due to the sampling time is too short, lead to the result not accurate enough？ I try to increase the value of DMAXSKIPPED, but will let the program became stuck