Messages in this thread | | | Date | Mon, 26 Jun 2006 12:00:48 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH] IPMI: use schedule in kthread |
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On Mon, 26 Jun 2006 09:08:19 -0500 MAILER-DAEMON@osdl.org wrote:
> The kthread used to speed up polling for IPMI was using udelay > when the lower-level state machine told it to do a short delay. > This just used CPU and didn't help scheduling, thus causing bad > problems with other tasks. Call schedule() instead. > > Signed-off-by: Corey Minyard <minyard@acm.org> > > Index: linux-2.6.17/drivers/char/ipmi/ipmi_si_intf.c > =================================================================== > --- linux-2.6.17.orig/drivers/char/ipmi/ipmi_si_intf.c > +++ linux-2.6.17/drivers/char/ipmi/ipmi_si_intf.c > @@ -809,7 +809,7 @@ static int ipmi_thread(void *data) > /* do nothing */ > } > else if (smi_result == SI_SM_CALL_WITH_DELAY) > - udelay(1); > + schedule(); > else > schedule_timeout_interruptible(1); > }
calling schedule() isn't a lot of use either.
If CONFIG_PREEMPT it's of no benefit and will just chew CPU.
If !CONFIG_PREEMPT && !need_resched() then it's a no-op and will chew CPU.
If !CONFIG_PREEMPT && need_resched() then yes, it'll schedule away. This is pretty much the only time that a simple schedule() is useful.
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