On Fri, 23 Aug 2002 11:09:28 +0200 Wank Rainer <Rainer.Wank@icn.siemens.de> wrote: WR> the Linux scheduler has three policies SCHED_FIFO, SCHED_RR and WR> SCHED_OTHER. SCHED_FIFO and SCHED_RR are for realtime requirements. Don't forget SCHED_NORMAL. Regarding SCHED_FIFO and SCHED_RR yes, they actually have a higher priority than other processes. The difference between the two policies is the way they'll compete for the CPU with each other. WR> There are also kernel threads, like [kswapd]. Does a kernel thread WR> have a priority? How does the scheduler schedule kernel threads? Check preempt_count. WR> On the other hand a process can also have several threads. Yes, but they are user-space threads (usually by a pthread or like implementation). WR> How does the scheduler schedule these threads in contrast to kernel WR> threads or processes? The kernel does not recognize user-space threads. They are processes. The thread sinchronization, mutual-exclusion and other thread stuff is done by a user-space library. So, to the scheduler, they're a bunch of child processes. Felipe -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
