Is is safe to just set the task state myself?
Spinlocks can give me mutual exclusion, but what I need to do is sleep
until there is something in the queue to process. This is a textbook
application of semaphores -- or is the kernel implementation of semaphores
not so textbook?
Matt Dharm
On Sat, Jun 03, 2000 at 08:49:02AM +0200, Francis GALIEGUE wrote:
> On Fri, 2 Jun 2000, Matthew Dharm wrote:
>
> > Hi! I'm working on the usb mass storage support for linux. For this, we
> > have a kernel thread which blocks on a semaphore (used to indicate the
> > number of commands in the queue).
> >
> > The problem is, when I block on the semaphore, the process is still marked
> > as runnable, and thus drives the load average up to 1.00. How do I sleep
> > so that I don't drive up the load? Or how do I mark the process as
> > sleeping on a semaphore for the purposes of load average calculation?
> >
>
> [ actually, I don't really know anything about kernel threads but ] my first
> guess is that blocking on a semaphore from a kernel thread doesn't set the task
> state to TASK_{UN,}INTERRUPTIBLE, this is why it keeps running.
>
> Can you use spinlocks in kernel threads? If yes, /methinks this is what you
> should use. My $0.02. Indeed, I'd appreciate being corrected.
>
> --
> fg
>
> "You can tune a filesystem but you can't tuna fish" (HP/UX' fsck manpage)
>
>
>
> -
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-- Matthew Dharm Home: mdharm@one-eyed-alien.net Senior Engineer, QCP Inc. Work: mdharm@qcpi.comM: No, Windows doesn't have any nag screens. C: Then what are those blue and white screens I get every day? -- Mike and Cobb User Friendly, 1/4/1999
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