Philippe Gerum wrote:
> On Thu, 2006-08-31 at 22:41 +0200, Gilles Chanteperdrix wrote:
> > Philippe Gerum wrote:
> > > On Wed, 2006-08-30 at 14:36 +0200, Philippe Gerum wrote:
> > > > -------- Forwarded Message --------
> > > > > From: Daniel Schnell <[EMAIL PROTECTED]>
> > > > > To: xenomai-help <[email protected]>
> > > > > Subject: Performance decrease
> > > > > Date: Wed, 30 Aug 2006 11:58:25 -0000
> > > > >
> > > > > Hi,
> > > > >
> > > > >
> > > > >
> > > > > I have made some CPU throughput tests with/without "Nucleus
> > options->pervasive real-time support in user-space"
> > > > enabled/disabled. And the performance dicrease in using that option
> > is for my processor (MPC5200, 400 MHz) about 10%.
> > >
> > > There is an impact induced by activating the user-space support, since
> > > all system calls are filtered through Xenomai; some work is currently
> > > undergoing to reduce this overhead, so that only system calls issued by
> > > Xenomai shadows would be intercepted. This said, out of curiosity, how
> > > do you measure those 10% on your board?
> >
> > Just being curious: how will you achieve this ? You will make the
> > function used to dispatch system calls a per-thread pointer ?
> >
>
> Syscalls are just another form of exceptions, so the change will need to
> affect all event notifications. A per-thread pointer is an opion
> provided there is also a mean to install the callback address, so we
> would also need to intercept the Linux task creation event.
If we continue on this idea. PTD initialization already intercept the
Linux task creation event to set the PTDs to 0. Maybe we could dedicate
a PTD to mean that a thread is "monitored", so that when an Adeos event
occurs, the event only triggers Xenomai callbacks if the thread is
monitored (not sure that it would work for the "schedule" event
though).
But there is an exception: the "bind" syscall event must be intercepted
for threads that are not yet marked as monitored.
--
Gilles Chanteperdrix.
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