Messages in this thread | | | From | "lk" <> | Subject | Re: How does 2.6 SMP scheduler initially assign a thread to a run queue? | Date | Wed, 8 Jun 2005 18:11:55 +0530 |
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> > In the 2.6 kernel, there is one run queue per CPU, in case of an SMP. > After a thread is created, how does the scheduler determine which run > queue it goes to?
First it forked process (child) gets the same CPU as that of parent. forking a child gets the same CPU and later part of fork will call wake_up_new_task () to fetch the run-queue of the CPU and __activate_task () is called to move task into run-queue. Later rescheduling of the process may move process to another run-queues.
>I know that once it goes to a particular run queue, > the scheduler would try to run that thread on that CPU to take > advantage of processor affinity; and then there would be the load > balancing stuff. But at the very beginning, what algorithm does the > scheduler use to assign a newly created thread to a particulat CPU?
Child will always goes to the parent's run-queue (CPU) for the first time.
> Would the load balancing algorithm be used? Or gang scheduling?
Yes, load balancing algorithm is used. tasks will be pulled from very busy processors to lesser busy processors.
> By the way, in an SMT/hyperthreading processor, does the latest kernel > version assign one run queue per physical CPU, or per virtual > processor? >
one run-queue per physical CPU
regards lk
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