lkml.org 
[lkml]   [2010]   [Aug]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [RFC PATCH 00/11] sched: CFS low-latency features
* Peter Zijlstra (peterz@infradead.org) wrote:
> On Thu, 2010-08-26 at 19:09 -0400, Mathieu Desnoyers wrote:
> > > WTF can't the damned delivery thread not be created when timer_create
> > > is called and the signal be delivered to that very thread directly via
> > > SIGEV_THREAD_ID ?
> >
> > Yeah, that sounds exactly like what I proposed about an hour ago on IRC ;) I'm
> > pretty sure that would work.
> >
> > The only thing we might have to be careful about is what happens if the timer
> > re-fires before the thread completes its execution. We might want to let the
> > signal handler detect these overruns somehow.
>
> Simply don't use SIGEV_THREAD and spawn you own thread and use
> SIGEV_THREAD_ID yourself, the programmer knows the semantics and knows
> if he cares about overlapping timers etc.

From man timer_create:

SIGEV_THREAD
Upon timer expiration, invoke sigev_notify_function as if it
were the start function of a new thread. (Among the implementa‐
tion possibilities here are that each timer notification could
result in the creation of a new thread, or that a single thread
is created to receive all notifications.) The function is
invoked with sigev_value as its sole argument. If
sigev_notify_attributes is not NULL, it should point to a
pthread_attr_t structure that defines attributes for the new
thread (see pthread_attr_init(3).

So basically, it's the glibc implementation that is broken, not the standard.

The programmer should expect that thread execution can overlap though.

Thanks,

Mathieu


--
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com
--
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: 2010-08-27 17:23    [W:0.073 / U:12.876 seconds]
©2003-2018 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site