Hi Arun, thank you for your answer and the explanation of completion variables and how the workers are used. It clearified those ideas for me and I feel safer using them now. Best regards, Tobias On 13.02.2017 11:01, Arun Sudhilal wrote: > Hello Tobias, > > On Sun, Feb 12, 2017 at 7:15 PM, Tobias FItschen > <tobias.fitschen@xxxxxxxxxxxxxxxxxxx> wrote: >> Hello people, >> >> I have a question regarding workqueues. I know it's possible to sleep in >> workqueue routines. Does that mean I can use: > What it means is that you are safe to use any sub routines which may > sleep or which will sleep. > >> 1. "set_current_state(TASK_INTERRUPTIBLE);" get the the task with >> "current" and pass it to a other task and then call "schedule();" in a >> workqueue routine and at a different place (perhaps another workqueue >> routine) use wake_up_process(task)" ? >> >> 2. initialize completions in a workqueue routine and call complete() in >> a different workqueue routine? >> >> I tried it in a simple example setup and both worked. I just want to > completion variables are written to hide the complexity of using > set_current_state and related functions to make a thread sleep. It > basically enables driver authors to reuse the same code for > sleep/wake. > At the heart of it, its all the same. My recommendation is to use completion. > >> make sure that was not just by accident. As I understand it a work item >> is executed on a worker, which is a unique process, but I also know that >> there are exceptions, e.g. I can not copy to or from user space in a >> workqueue routine. Also I don't know if a worker "sticks" with the >> current work item until it is completed or can execute multiple work >> items at the "same" time. > Yes a kworker sticks with current work item until it is completed. If > a work item currently executed by a worker met with a sleep, another > kworkers are used to process the other pending work items. > > Regards, > Arun > >> 3. In case completions and schedule()/wakeup() work, I would also like >> to know, which has the better performance. >> >> Thanks a lot already! >> >> Tobias >> >> >> _______________________________________________ >> Kernelnewbies mailing list >> Kernelnewbies@xxxxxxxxxxxxxxxxx >> https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
