Re: revivesa status 2008/07/09

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

On Fri, Jul 11, 2008 at 12:47:45PM +0000, Andrew Doran wrote:
> On Thu, Jul 10, 2008 at 11:39:12AM -0700, Bill Stouder-Studenmund wrote:
> > On Thu, Jul 10, 2008 at 10:28:44AM +0300, Andy Shevchenko wrote:
> > > On Thu, Jul 10, 2008 at 9:31 AM, Bill Stouder-Studenmund
> > > <wrstuden%netbsd.org@localhost> wrote:
> > > > Today's code (actually last weekend's; I've been AFK for a bit) now 
> > > > passes
> > > > all of the NetBSD 4.0 libpthread regression tests! As such, I think the
> > > > branch is an overall success.
> > > What about VSTHlite to be included to the bunch of regression tests?
> > > Some discussion about it here:
> > > http://mail-index.netbsd.org/tech-misc/2008/06/24/msg000046.html
> > 
> > That's a separate discussion. The goal of the revivesa branch is to 
> > implement support for the Scheduler Activations system calls used by the 
> > SA libpthread in NetBSD 4.x.
> 
> It has to be said, I have not seen a convincing explanation as to why this
> is desirable or in the best interests of NetBSD as a product.
> 
> SA threading in NetBSD has serious problems and drawbacks. For example:
> 
> - it works only on a handful of architectures, eg x86.
> - in most tests its performance is demonstrably inferior to 1:1.
> - it's completely unreliable, even opening the machine to DOS attacks.
> - it has architectural, code quality and code maintenance issues.
> - it completely lacks any kind of real-time support.
> 
> In its current form SA threading is a regressive proposition. Even if all
> the remaining issues are addressed, what benefits would it bring over and
> above 1:1 threading?

Be able to run a netbsd-4 or netbsd-3 userland on a netbsd-5 kernel.

-- 
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference
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