Re: hardcoded HZ in hub.c

From: Andrew Morton (andrewm@uow.edu.au)
Date: Wed Nov 22 2000 - 06:22:01 EST


David Woodhouse wrote:
>
> johannes@erdfelt.com said:
> > Multiple seconds in the worst case.
>
> Well, I think the PCMCIA socket drivers would be happy with that. Depends
> what akpm also added to the list of tasks,

Nothing which sleeps for very long - mainly serial drivers which queue
a call to tty_hangup(), which immediately queues _another_ tq_scheduler
call to do_tty_hangup (Why? Heaven knows).

> and whether Linus actually puts
> that patch into test12.

tq_scheduler is a bug. You can't sleep, you can't call copy_*_user,
you can't call kmalloc non-atomically. But we do do these things.
Really the only reason for using tq_scheduler is so you can acquire
the tasklist_lock or the files_lock. schedule_task() is fine for that.

tq_scheduler must die.
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