lkml.org 
[lkml]   [2006]   [Jul]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: A better interface, perhaps: a timed signal flag
From
Date
On Fri, 2006-07-28 at 17:41 +0100, Alan Cox wrote:
> Ar Gwe, 2006-07-28 am 10:52 -0400, ysgrifennodd Theodore Tso:
> > Good point, and limiting this facility to one such timeout per
> > task_struct seems like a reasonable restriction.
>
> Why is this any better than using a thread or signal handler ? From the
> implementation side its certainly horrible - we will be trying to write
> user pages from an IRQ event. Far better to let the existing thread code
> deal with it.
>

If the user page is special, in that it is really a kernel page mapped
to userspace. The implementation on making sure it doesn't disappear on
the interrupt isn't that difficult.

But for real-time applications, the signal handling has a huge latency.
Where as what Theodore wants to do is very light weight. ie. have a
high prio task doing smaller tasks until a specific time that tells it
to stop. Having a signal, would create the latency on having that task
stop.

These little requests make sense really only in the real-time space.
The normal uses can get by with signals. But I will say, the normal
uses for computing these days are starting to want the real-time
powers. :)

-- Steve


-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2006-07-28 18:49    [W:2.488 / U:0.356 seconds]
©2003-2011 Jasper Spaans. Advertise on this site