lkml.org 
[lkml]   [2005]   [Feb]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: Xterm Hangs - Possible scheduler defect?
> `xterm' is waiting for the other CPU to schedule a kernel thread (which is
> bound to that CPU). Once that kernel thread has done a little bit of work,
> `xterm' can terminate.
>
> But kernel threads don't run with realtime policy, so your userspace app
> has permanently starved that kernel thread.
>
> It's potentially quite a problem, really. For example it could prevent
> various tty operations from completing, it will prevent kjournald from ever
> writing back anything (on uniprocessor, etc). I've been waiting for
> someone to complain ;)
>
> But the other side of the coin is that a SCHED_FIFO userspace task
> presumably has extreme latency requirements, so it doesn't *want* to be
> preempted by some routine kernel operation. People would get irritated if
> we were to do that.
>
> So what to do?

It shouldn't need to preempt the kernel operation. Why is the design such that
the necessary kernel thread can't run on the other CPU?

Chad
-
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: 2005-03-22 14:10    [W:0.046 / U:0.344 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site