Victor Yodaiken <yodaiken@fsmlabs.com> writes:
> On Mon, Oct 08, 2001 at 07:59:05PM +0530, BALBIR SINGH wrote:
> > BTW, that brings me to another issue, once the kernel becomes preemptibel,
> what
>
> > are the locking issues? how are semaphores and spin-locks affected? Has
> anybody
>
> > defined or come up with the rules/document yet?
>
> IF the kernel becomes preemptible it will be so slow, so buggy, and so painful
> to maintain, that those issues won't matter.
The preemptible kernel work just takes the current SMP code, and
allows it to work on a single processor. You are not interruptted if
you have a lock held. This makes the number of cases in the kernel
simpler, and should improve maintenance as more people will be
affected by the SMP issues.
Right now there is a preemptible kernel patch being maintained
somewhere. I haven't had a chance to look recently. But the recent
threads on low latency mentioned it.
As for rules. They are the usual SMP rules. In earlier version there
was a requirement or that you used balanced constructs.
i.e.
spin_lock_irqsave
...
spin_unlock_irqrestore
and not.
spin_lock_irqsave
...
spin_unlock
..
restore_flags.
Eric
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This archive was generated by hypermail 2b29 : Mon Oct 15 2001 - 21:00:18 EST