[lkml]   [1997]   [Apr]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: RT-Linux and SMP

On Thu, 24 Apr 1997, Victor Yodaiken wrote:
> Sure. But you are permitting two interrupts to execute at the same time
> as long as neither invokes cli. So what prevents those two routines from
> modifying each others data? If interrupt routines executing in non-cli
> mode can modify shared data, wouldn't this cause a problem for SMP and
> even in the single processor case?

Two interrupts can run at the same time even under UP ("same time" in a
very limited sense, obviously - but one interrupt can interrupt the
other). As such, if we are ever in a critical section where this makes a
difference, that critical section obviously has to do a cli/sti.

And they do.

> In any event, I think that the rtlinux soft-interrupts fits into this
> scheme quite well and should make the irq_lock unecessary.

I don't believe you can make the irq_lock unnecessary - _something_ like
that is needed anyway.


 \ /
  Last update: 2005-03-22 13:39    [W:0.033 / U:15.384 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site