[TAPSETS] Linux Kernel Event Trace Tool

[Guanglei Li]

> Hien Nguyen wrote:
>
> >2. Like Frank once commented,consider using printf for some of the 
> >logtrace functions,so we could emplement them in script instead of 
> >embeded C. For example, the log_tracedata_common() function could 
> >implement in script as follow
> >  printf("%d|%d|%d|%d|%d|%d\n", gettimeofday_ms(), pid(), ppid(), 
> > tid(), cpuid(), hoodID)
> >
> > [...]
> >
> >3. Consider using gettimeofday_s() for second, gettimeofday_ms()
> > for millisecond, gettimeofday_ns() for naosenconds etc... They are 
> > new code under tapset, so you may not be aware.
> >
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Thanks. In fact one reason of using embedded c tapsets is because I 
can get values directly by accessing a variable, which is cheaper than 
calling functions such as pid(), tid(), stp_pid() etc.

Another factor I considered is that some embedded c tapsets seem not 
easy to be replaced by a equivalent stap script, e.g. 
log_ioscheduler_tracedata_extra_elv_next(). To keep all my codes 
consistent, I use log_tracedata_common() and log_tracedata_xxx_extra() 
for all events.

Frank suggested making those embedded c functions to returns a string, 
which the caller script routine could print, so that we can keep as 
much logic as possible in script. The codes of mine hide the logging 
details inside those embedded c functions. I am not sure which of 
these two are better, any suggestions?