Commit Graph

2 Commits

Author SHA1 Message Date
Dmitry Chagin
81338031c4 Switch linuxulator to use the native 1:1 threads.
The reasons:
1. Get rid of the stubs/quirks with process dethreading,
   process reparent when the process group leader exits and close
   to this problems on wait(), waitpid(), etc.
2. Reuse our kernel code instead of writing excessive thread
   managment routines in Linuxulator.

Implementation details:

1. The thread is created via kern_thr_new() in the clone() call with
   the CLONE_THREAD parameter. Thus, everything else is a process.
2. The test that the process has a threads is done via P_HADTHREADS
   bit p_flag of struct proc.
3. Per thread emulator state data structure is now located in the
   struct thread and freed in the thread_dtor() hook.
   Mandatory holdig of the p_mtx required when referencing emuldata
   from the other threads.
4. PID mangling has changed. Now Linux pid is the native tid
   and Linux tgid is the native pid, with the exception of the first
   thread in the process where tid and pid are one and the same.

Ugliness:

   In case when the Linux thread is the initial thread in the thread
   group thread id is equal to the process id. Glibc depends on this
   magic (assert in pthread_getattr_np.c). So for system calls that
   take thread id as a parameter we should use the special method
   to reference struct thread.

Differential Revision:	https://reviews.freebsd.org/D1039
2015-05-24 14:53:16 +00:00
Alexander Leidinger
19e252baeb - >500 static DTrace probes for the linuxulator
- DTrace scripts to check for errors, performance, ...
  they serve mostly as examples of what you can do with the static probe;s
  with moderate load the scripts may be overwhelmed, excessive lock-tracing
  may influence program behavior (see the last design decission)

Design decissions:
 - use "linuxulator" as the provider for the native bitsize; add the
   bitsize for the non-native emulation (e.g. "linuxuator32" on amd64)
 - Add probes only for locks which are acquired in one function and released
   in another function. Locks which are aquired and released in the same
   function should be easy to pair in the code, inter-function
   locking is more easy to verify in DTrace.
 - Probes for locks should be fired after locking and before releasing to
   prevent races (to provide data/function stability in DTrace, see the
   man-page of "dtrace -v ..." and the corresponding DTrace docs).
2012-05-05 19:42:38 +00:00