lkml.org 
[lkml]   [2004]   [Oct]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [patch] Real-Time Preemption, -VP-2.6.9-rc4-mm1-U0

* Karim Yaghmour <karim@opersys.com> wrote:

>
> Ingo Molnar wrote:
> > http://redhat.com/~mingo/voluntary-preempt/voluntary-preempt-2.6.9-rc4-mm1-U0
>
> I notice:
> + local_irq_save(flags);
> + ____trace(&__get_cpu_var(trace), eip, parent_eip);
> + local_irq_restore(flags);
>
> Why not use the lockless logging available in relayfs, you'll avoid
> the interrupt disabling altogether since, umm ... it's lockless.

i just added something ad-hoc. I wanted it to be accurate across
interrupt entries. I have not looked at the relayfs locking but how does
it solve that? Also, cli/sti makes it obviously SMP-safe and is pretty
cheap on all x86 CPUs. (Also, i didnt want to use preempt_disable/enable
because the tracer interacts with that code quite heavily.)

Ingo
-
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 14:07    [W:0.578 / U:1.292 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site