On 3/18/08, Arvin Moezzi <moezzia@xxxxxxxxx> wrote: > On 3/17/08, Peter Teoh <htmldeveloper@xxxxxxxxx> wrote: > > Looking at schedule_work() below: > > > > fs/file.c: > > > > fddef = &get_cpu_var(fdtable_defer_list); > > spin_lock(&fddef->lock); > > fdt->next = fddef->next; > > fddef->next = fdt; > > /* vmallocs are handled from the workqueue context */ > > schedule_work(&fddef->wq);===> > > spin_unlock(&fddef->lock); > > > > can schedule_work() sleep? if so, then holding a spin_lock (which is > > supposed to be used for quick turnaround operation) across a sleepable > > functions look risky here (though it is possible to design this way, > > but the classic CPU 100% bug is possible - sleep and never wake up, > > resulting in another CPU going into spin_lock mode - churning up 100% > > CPU time). Or may be I am wrong? > > > > Can calling this function schedule_work() ever ended the entire task > > being reassigned to another CPU? If so, then, will it not defeats > > the purpose of using the per_cpu function get_cpu_var()? > > > > How about schedule() -->ever ended the entire task being reassigned to > > another CPU? ? > > > > > Hey Peter, > > btw. have you found out whether or not a "spin_lock" after "get_cpu_var" > makes sense. I couldn't understand it either. > > > Arvin > Discussion thread is here: http://www.gossamer-threads.com/lists/linux/kernel/892870?do=post_view_flat#892870 I am still replying his email.......trying to understand these.... -- Regards, Peter Teoh -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
