Messages in this thread | | | Date | Thu, 1 Jul 2004 14:06:24 +0200 | From | Ingo Molnar <> | Subject | Re: Linux scheduler (scheduling) questions vs threads |
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* Povolotsky, Alexander <Alexander.Povolotsky@marconi.com> wrote:
> Sorry for bothering and annoying everyone on this list again with additional > questions ... > > Let assume there is one (and only one) application (user space ) process > running on the Linux 2.6 - with multiple threads within it, created via > "clone" (this happens, I presume, for example, if one uses Monta Vista > library for porting PSOS to Linux). > > What scheduling policies those threads (within the same process) will be > governed by (if any )?
in Linux there's no difference between the scheduling of 'threads' and 'processes'. Both are internally a 'task'. If two tasks share the same MM (this is possible via the use of clone()) then they are called threads. If a task has its own MM (normally created via fork()) then it's called a process - but the scheduler doesnt care.
so the normal Linux scheduling policy applies to 'threads' too. Fully preemptable, SCHED_NORMAL by default, or SCHED_FIFO/SCHED_RR if you set it. The priority (or rt_priority) can be set per-task as well. Newly created threads/processes may inherit (or not) the policy of the parent, this largely depends on the library implementation.
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