Messages in this thread | | | Date | Wed, 26 Jun 2002 10:17:45 -0400 (EDT) | From | "Richard B. Johnson" <> | Subject | Re: Problems with wait queues |
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On Wed, 26 Jun 2002, Nicolas Bougues wrote:
> On Wed, Jun 26, 2002 at 12:52:41PM +0200, Andries Brouwer wrote: > > On Wed, Jun 26, 2002 at 12:32:43PM +0200, Nicolas Bougues wrote: > > > > > Does anybody have any idea on what I may have done wrong, and why > > > would loadavg increase when vmstat show no activity ? > > > > loadavg does not report what you think it reports > > > > As far as I understand, loadavg reports the average number of > processes in the TASK_RUNNING state. > > What happens in my driver, I believe, is that : > - on timer interrupt, I do some stuff, and wake_up the waiting process > - then the loadavg is computed (seeing my waiting task as TASK_RUNNING) > - then the scheduler runs the task > - then the task goes immediatly back to sleep > > >From this point of view, then my problem is just "cosmetic". Isn't > there a way to do things in a different order, so that I could still > get a meaningful(*) loadavg ? > > (*): by meaningful, I mean representing the number of busy processes > at a random point in time. > -- > Nicolas Bougues >
I am sure that you can have things look correct as well as run properly. However, you didn't show us the code. You need to do something like:
interruptible_sleep_on(&semaphore);
while your wake-up occurs with:
wake_up_interruptible(&semaphore);
Or, you can do (the hard way) :
while(!something) { current->policy |= SCHED_YIELD; schedule(); }
Both ways (and others) will look fine with `top` and will sleep properly.
Cheers, Dick Johnson
Penguin : Linux version 2.4.18 on an i686 machine (797.90 BogoMips).
Windows-2000/Professional isn't.
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