Hello everybody:
I have been trying to differenciate threads and process in Linux. As
I am sure you already know, other OS, namely HPUX, implement threads
in a different way. There is a thread id (TID) field in the structure
that is used by the scheduler and it is used to identify uniquely each
"task" that can be run. Using this structure makes easier to identify
which threads belong to the same process and tools such as ps or top
show the TID as a field.
I understand that changing this in the Linux kernel would mean that:
* some tools will have to be modified.
* the proc filesystem should create a directory using the TID instead
of the PID.
* some features as VM handling, signaling or exec()ing from a thread
would be more difficult to implement.
* compatibility will be broken.
However, I miss some way to indicate that two processes are, in
fact, threads of the same process. Maybe there is something I'm
missing. Let me elaborate this.
If you run 'top' (sorted by memory usage) and, lets say, you have 9
threads, you see the SIZE of these 4 threads
10:40am up 1:23, 1 user, load average: 0.26, 0.22, 0.10
52 processes: 51 sleeping, 1 running, 0 zombie, 0 stopped
CPU states: 0.0% user, 3.1% system, 0.0% nice, 96.8% idle
Mem: 322464K av, 306284K used, 16180K free, 16876K shrd, 32432K
buff
Swap: 530136K av, 8064K used, 522072K free 13660K
cached
PID USER PRI NI SIZE RSS SHARE STAT LIB %CPU %MEM TIME COMMAND
745 root 0 0 224M 217M 1596 S 0 0.0 68.9 0:00
traffic_mana
840 root 15 0 224M 217M 1596 S 0 0.0 68.9 0:00
traffic_mana
841 root 0 0 224M 217M 1596 S 0 0.0 68.9 0:13
traffic_mana
846 root 0 0 224M 217M 1596 S 0 0.0 68.9 0:00
traffic_mana
848 root 0 0 224M 217M 1596 S 0 0.0 68.9 0:00
traffic_mana
850 root 0 0 224M 217M 1596 S 0 0.0 68.9 0:00
traffic_mana
855 root 0 0 224M 217M 1596 S 0 0.0 68.9 0:00
traffic_mana
856 root 0 0 224M 217M 1596 S 0 0.0 68.9 0:00
traffic_mana
857 root 0 0 224M 217M 1596 S 0 0.0 68.9 0:00
traffic_mana
This information is missleading since there is no way to know that
these 9 threads are sharing memory. If you run 'ps axl' you can see
the hierarchy as if it was a multiprocess program, i.e. no difference
to show you that they are threads. Not even reading
/proc/<pid>/status you get info about these being threads.
Of course, I am talking about kernel 2.2.x, but AFAIK this has not
changed in the new kernels.
Would it make sense to include this as an entry of the /proc/<pid>?
Thanks for reading,
Jorge
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This archive was generated by hypermail 2b29 : Wed Mar 07 2001 - 21:00:19 EST