Messages in this thread | | | Date | Tue, 26 Feb 2002 12:50:41 -0800 (PST) | From | Davide Libenzi <> | Subject | Re: schedule() |
| |
On Tue, 26 Feb 2002, Richard B. Johnson wrote:
> On Tue, 26 Feb 2002, Davide Libenzi wrote: > > > On Tue, 26 Feb 2002, Richard B. Johnson wrote: > > > > > On Tue, 26 Feb 2002, Davide Libenzi wrote: > > > > > > > On Tue, 26 Feb 2002, Richard B. Johnson wrote: > > > > > > > > > > > > > > > > > > > I just read on this list that: > > > > > > > > > > while(something) > > > > > { > > > > > current->policy |= SCHED_YIELD; > > > > > schedule(); > > > > > } > > > > > > > > > > Will no longer be allowed in a kernel module! If this is true, how > > > > > do I loop, waiting for a bit in a port, without wasting CPU time? > > > > > > > > > > A lot of hardware does not generate interrupts upon a condition, > > > > > there is no CPU activity that could send a wake_up_interruptible() > > > > > to something sleeping. > > > > > > > > > > For instance, I need to write data to a hardware FIFO, one long-word > > > > > at a time, but I can't just write. I have to wait for a bit to be > > > > > set or reset for each and every write. I'm going to be burning a > > > > > lot of CPU cycles if I can't schedule() while the trickle-down-effect > > > > > of the hardware is happening. > > > > > > > > What did it do yield() to you ? Doesn't it work for your case ? > > > > > > > There isn't one in 2.4.x I'll modify my drivers to use YIELD > > > and #define it depending upon version. > > > > In 2.5 yield() maps to sys_sched_yield(). You can handle it in the same > > way in your includes if version <= 2.4. > > > > > > Can't find it in any header file. > > Script started on Tue Feb 26 15:45:06 2002 > # grep "sys_sched_yield()" /usr/src/linux/include/linux/*.h > # grep "sys_sched_yield()" /usr/src/linux/include/asm/*.h > You have new mail in /var/spool/mail/root > # exit > exit > > Script done on Tue Feb 26 15:46:46 2002 > > I'll #define a macro and be done with it.
It'd be too easy if it'd be inside an header file :-)
asmlinkage long sys_sched_yield(void);
in kernel/sched.c
- Davide
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |