[Bug translator/10045] New: process.syscall(NUM) probes

[fche at redhat dot com]

In the future, we will probably extend or twin the syscall.* tapset
to utrace-based high-performance probes.  However, utrace per se doesn't
provide efficient per-syscall-type filtering, so if it were implemented
thusly:

probe process.syscall.read = process.syscall {
  if ($syscall_nr!=30) next
  arg1=@cast(...)
}
....

then multiple syscall probes can't be very efficiently implemented,
since it would translate to a chain of if/else's or worse, just to
evaluate the syscall_nr comparison/rejection logic.

If OTOH the syscall number was pushed into the probe point, as in
  probe process.syscall(NUM) {...}
then the translator can emit a more efficient switch block in case
of multiple syscall probes.

-- 
           Summary: process.syscall(NUM) probes
           Product: systemtap
           Version: unspecified
            Status: NEW
          Severity: normal
          Priority: P2
         Component: translator
        AssignedTo: systemtap at sources dot redhat dot com
        ReportedBy: fche at redhat dot com


http://sourceware.org/bugzilla/show_bug.cgi?id=10045

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