Messages in this thread | | | Date | Tue, 26 Feb 2002 12:19:58 -0800 (PST) | From | Davide Libenzi <> | Subject | Re: schedule() |
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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.
- Davide
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