[Bug runtime/14691] New: the task_finder vma tracking could use individual syscall tracepoints

[Bug runtime/14691] New: the task_finder vma tracking could use individual syscall tracepoints

[dsmith at redhat dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=14691

             Bug #: 14691
           Summary: the task_finder vma tracking could use individual
                    syscall tracepoints
           Product: systemtap
           Version: unspecified
            Status: NEW
          Severity: enhancement
          Priority: P2
         Component: runtime
        AssignedTo: systemtap@sourceware.org
        ReportedBy: dsmith@redhat.com
    Classification: Unclassified


Currently, when vma tracking is needed, the task_finder turns on syscall
tracing to keep track of mmap()/munmap() calls. Unfortunately, this slows down
every syscall.

Instead, if CONFIG_FTRACE_SYSCALLS is enabled, the task_finder could attach to
the individual mmap()/munmap() tracepoints.

As a comment states in task_finder2.c:

/* FIXME: in the brave new world, we'll use target individual
 * syscalls, instead of tracing all syscalls for the map stuff.
 * However, process.syscall will still need to target all syscalls. */

(Note that this enhancement doesn't depend on bug #14689, since from the C
runtime we should be able to use the "syscalls" tracepoints.)

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[Bug runtime/14691] the task_finder vma tracking could use individual syscall tracepoints

[dsmith at redhat dot com]

http://sourceware.org/bugzilla/show_bug.cgi?id=14691

David Smith <dsmith at redhat dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |WONTFIX

--- Comment #1 from David Smith <dsmith at redhat dot com> 2012-10-10 16:14:00 UTC ---
Playing around with this, I find it is actually impossible to attach to these
syscall tracepoints from C since they aren't declared anywhere.  Plus, since it
looks like they just may be multiplexed inside the "raw" syscall tracepoints,
there wouldn't be any performance improvement using the individual syscall
tracepoints.

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